1

INVESTMENT IN AS A CHALLENGE FOR R&D

H. Harms Lenzing AG, A – 4860 Lenzing, e-mail: [email protected]

The recent announcements of Lenzing AG to 1980s when the world was said to be still expand its Austrian viscose plant in doing well (figure 1). It is also commodities, Lenzing and its Lyocell fiber plant in such as polyester staple, where in spite of several Heiligenkreuz; Austria, came somewhat as a plant closures by traditional producers even surprise to the textile world. It seems that the small entrepreneurs identified business community believes that the current state of the opportunities and started investing in new industry could only produce news of plant grassroots capacities. The face value of the closures. Some of the players obviously fail to market assessment of many of the key players understand a decision to increase fiber capacities clearly does not reflect the whole picture! in Western Europe. For Lenzing it will be an 800 increase of more than 100.000 tons/year in less Viscose, Modal, Lyocell than a decade, which is more than just 700 PES staple compensating for the cumulative reductions of 600 other producers within the same period. The 500 question remains whether Lenzing is an 400 exception or whether it would have been better to follow the trend. 300 200 There have been a considerable number of plant closures in recent years. Many of the big, 100 traditional fiber producers have completely given 0 up their activities in the fiber field. Their market 1990 1992 1994 1996 1998 2000 2002 2004 analysis has taught them about the long-term Figure 1. Production capacities in Western Europe (tpa). shrinking consumption of their established products and the increased pressure on the margins. The consequence in most cases was a Everybody knows that there has been a huge “milking strategy”, sooner or later ending in mill change in the structure of the markets and there closures during one of the next downs in the are good reasons for the depressed moods of business cycle, often with the expectation of a many players in the industry. It is true that the better utilization of the remaining capacities. migration of textile manufacturing to cheap-labor However the pessimistic message of this type of countries has completely changed the scenarios. withdrawals often resulted in the complete The textile industry has been shaken and is still disappearance of the corresponding markets. being shaken by the pressure of cheap imports. Also Lenzing had to suffer from this type of The market is neither willing nor able to continue decisions when their renowned joint venture paying the profit margins for standard products partner insisted in closing their joint polyester expected by the fiber producers. But is reduction staple fiber plant in Austria. of capacities the only possible consequence of But is it really true that Europe is inevitably such a process? The future of the industry rather caught in the same trend as the US, where the seems to deal with the old issues of taking up a textile industry and the fiber producers servicing challenge and working on converting it into a it almost disappeared in the last decade? chance by starting with the “home exercise” to Surprisingly not only are capacities in man-made reduce the cost basis, to solve environmental cellulosics increasing again in Western Europe, problems, to adjust the quality to the increasingly reaching levels even above those of the late demanding downstream processing technologies, 2 to find new market segments, and to support the specialty market segments. Micro-fibers, spun- customers in doing this by offering new dyed fibers, UV-protection and flame retardant innovative fibers! But of course this is not properties are but a few of the features in that suitable for a “milking strategy”! Lenzing´s field. New fibers with further enhanced moisture capital investments, exceeding the 100 million absorbency and water retention are servicing Euro level, can only be understood in view of additional nonwovens and technical applications, many years of this type of “home exercise” - and which are presently the fastest growing market a lot of it has to do with constant investment in segments in Western Europe. A new fiber with R&D. Lenzing has been able to solve the improved dyeing properties offers substantial environmental challenges inherent to the advantages to the downstream processing technologies employed and now is a model for industries and to fashion designers. environmentally friendly viscose fiber In contrast to the widespread opinion, there are production. Innovative processes have been several examples that companies producing or developed to produce fine chemicals from former processing fibers in Western Europe still have a pulping process emissions, which now chance to prosper, if they take the challenge and considerably reduce the costs for dissolving pulp, refocus on the traditional strengths of European the major raw material. manufacturing industries. The recent incidents in Continuous development efforts have resulted in some of the service- and “new markets”- a significant improvement of Lenzing´s product industries in the US have shown that benchmarks portfolio. The wide technological basis available of continuous upward trends are not realistic, to Lenzing - with the viscose, modal, and despite occasional impressions that this is so. recently the Lyocell process - offers wide We have good chances if we concentrate on possibilities for producing all the variety of fibers flexibility, efficiency and diversification, on for the special needs of the market. It is because innovative products and new technologies. One of a drastic improvement of the technological of the strongest assets in this context is the properties that they are able to meet the excellent education of the available work force. demanding needs of today’s high performance But this also requires a culture of stability and textile industries in Western Europe. Support of long-term thinking. Similar to production plants, innovative looks, new drapes, new hands and which cannot not work without proper special effects are equally crucial for success in maintenance and capital expenditures, innovative the fast-changing and fashion-driven textile products and new technologies will not be world. available without consistent R&D as well as an From about 30% only 10 years ago, Lenzing is efficient and flexible high-quality work force, now selling more than 60% of its production into which also requires proper care and handling. 3

VISCOSE STAPLE FIBER - HISTORY AND TRADE FLOW OF FIBER AND DOWNSTREAM TEXTILE PRODUCTS

Franz Kogler Feldweg 1, A – 4890 Frankenmarkt, Austria

Production and consumption of viscose 2000 staple fiber 1500 Viscose staple fiber still plays a significant role in the world fiber market, although if we look 1000 Eastern Europe back 30 years, it lost market share to the fast others growing synthetic fibers and cotton. Total 500 world fiber consumption increased from 22 0 million tons in 1970 to over 50 million tons in 1970 1980 1990 2000 2001. This includes both natural and man-made fibers, staple and filaments (Figure 1). Figure 3. Viscose consumption increased.

30 As with other fibers, viscose staple fiber mill consumption moved significantly to Asia from 25 other parts of the world (Figures 4 and 5). Today, 20 Viscose Staple the Asian countries account for three quarters of 15 Wool Cotton the world mill consumption of viscose staple for 10 other MMF textile applications, while Western Europe is 5 dominant in mill consumption for nonwovens 0 1970 1980 1990 2000 applications (Figure 6).

Figure 1. World consumption of fibers. 1600 1400 Viscose staple consumption was 2 million tons 1200 1000 Asia worldwide in 1970 and was only 1.6 million in 800 2001, mainly due to a sharp decline in Eastern 600 Rest of the Europe after the political changes in the late 400 World 1980s. In fact, viscose staple consumption has 200 0 grown slightly, if we disregard the development 1970 1980 1990 2000 in Eastern Europe (Figures 2 and 3). Figure 4. Shift of viscose staple fiber consumption to Asia.

1600 2500 1400 others 2000 1200 Eastern Europe 1500 1000 ASIA 800 1000 North America 600 Nonwovens 500 Western Europe 400 0 200 1970 1980 1990 2000 0 1996 1997 1998 1999 2000 2001

Figure 2. World consumption of viscose staple went Figure 5. Nonwovens share of world consumption of down mainly due to development in Eastern Europe. viscose staple is rising. 4

1000 400

800 300

600 200 Textile 100 Production 400 Nonwovens 0 Net Trade 200 -100 0 WE USA Asien Übrige

Figure 6. Asia processes 75 % of viscose staple for textiles, Western Europe is dominant in nonwovens. Figure 8. Viscose fiber trade flow 2000.

China, Western Europe, and are 1200 the countries with the highest mill consumption 1000 of viscose staple fiber today, followed by the 800 USA, Taiwan, , Japan, Thailand and 600 Production Korea. These 10 countries accounted for 90 % 400 Mill of the total world consumption in 2000, as 200 Consumption showninFigure7. 0

400 350 300 Figure 9. Within the trade blocs, production and 250 consumption of viscose staple is rather balanced. 200 150 Yarn Trade Flow 100 50 0 The effects of globalization can also be seen in the substantial trade of viscose spun yarns. India, Indonesia and Thailand are the most important net-exporters today. Western Europe and Figure 7. Viscose mill consumption – the top 10 also are important export countries, but with high countries account for 90 % of the world consumption in imports actually net importers. Importing 2000. countries with hardly any viscose spun yarn exports are South Korea, USA, Turkey and Japan. Fiber Trade Flow Taiwan’s imports and exports are approximately balanced. In total, the imports and exports of the With textile activities moving towards the Far top 10 countries shown in Figure 10 add up to East in the past 20 to 30 years, fiber capacities 150.000 tons each. have also been established in Asia. Compared to the “old days” when Europe, Japan and the USA used to export huge quantities of viscose 60 staple, today the net fiber trade volumes are 40 relatively small, as shown in Figure 8 for the 20 top 10 countries. The most important net- Export 0 exporters are Western Europe, Taiwan, Import Thailand and Indonesia; the major net- -20 importers are Turkey, China and South Korea. -40 There are substantial volumes of fibers moving -60 around the world, but in terms of net trade the situation is relatively balanced. This is particularly true if we look at trade blocks Figure 10. The total of yarn imports and exports is balanced with 150.000 tons each in the year 2000. rather than individual countries (Figure 9). 5

Fabric Trade Flow last few years. This effect may partly be the result of more fabrics being used in their own “making- As shown in Figure 11, there is significant trade up” industry in countries, such as China and in viscose fabrics, though declining over the Indonesia.

RAYON FABRIC (pure & blends) 000 tons IMPORTS/EXPORTS

200 190 180 170 160 150 140 130 120 110 100 EXPORT 90 80 70 60 50 40 30 20 10 0 -10 -20 -30 IM P O R TS -40 -50 -60 -70 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 94 95 96 97 98 99 2000 2000 2000 Western2000 2000 2000 2000 2000 2000 China Taiwan South Indonesia Turkey Japan USA Thailand Europe

Figure 11. fabric imports and exports.

If we again look at the most important viscose Final consumption of products made of viscose markets in the year 2000, we see exports of 300 staple fiber thousand tons of viscose fabrics – double the volume of yarn trade –, but imports of only 165 There are no statistics available that would show thousand tons (Figure 12). The balance is fabric the trade flow of garments made of viscose staple export to typical garment manufacturing fiber. However, based on estimates we can countries in Asia, Eastern Europe, North Africa, conclude that Western Europe and the United Near/Middle East and South/Central America. States still are the most important consumer markets for final products made of viscose fiber. 120 Together they account for approximately 40 % of 100 total world consumption, compared to a 10 % 80 share of world population. Western Europe sticks 60 out with an estimated share of 26 % of world 40 Exports consumption of final viscose products, compared to 6 % share of world population. These numbers 20 Imports refer to final consumption of all viscose staple 0 thousand tons fiber products, both textile and nonwovens in the -20

USA year 2000. Looking at the textile sector only, Japan -40 China Taiwan import penetration is increasing in these major Thailand -60 consumer markets, particularly in the United States and mainly in the form of ready-made Figure 12. Total exports of viscose fabrics were 300.000 garments. Comparing final consumption of tons compared to 165.000 tons imports in the year 2000. viscose textile products with mill consumption of viscose staple fiber for textile applications, the Thereisadistinctivedifferenceinthetrade import penetration in 2000 was 46 % in Western pattern between grey fabrics and finished Europe and already 76 % in the United States, and fabrics. China is by far the largest exporter of growing. grey viscose fabrics, followed by Indonesia. It will be interesting to watch the development The bulk of these grey fabrics go to Western after all quotas will be eliminated in 2005 as a Europe, South Korea, Thailand and Turkey, result of the Uruguay round. from where a substantial part is re-exported in form of finished, dyed or printed fabrics. 6

IMPORTANT TRENDS AFFECTING THE ASIAN VISCOSE MARKET

Craig Barker South Pacific Viscose, Desa Cicadas, P.O. Box 11 PWK, Purwakarta 41101, Indonesia

Introduction regions indefinitely. With the development of regional trade pacts, the situation has clearly The recent development of regional trade blocks, changed and Asian producers must now brace such as NAFTA, is having a huge impact on themselves for reducing exports to these regions Asian textile producers. As a result, viscose in the future (Figures 1 - 3). textile product producers will have to look at their present strategies to find new competitive US Textile and Apparel Imports in SME Mexico advantages to sustain their business in the future. Candada 5 China Development of trade blocks 4 Pakistan Taiwan 3 With the implementation of NAFTA at the end South Korea 2 of the 1990s, the textile imports into the USA India Bil. SME 1 have made a drastic shift to Mexico and the Hong Kong Caribbean Basin suppliers. Imports from China 0 Thailand and other Asian producers have dropped 1994 1999 Indonesia dramatically. They have lost significant market Figure 1. Mexico became the leading textile and apparel share to Mexico. With the implementation of the exporter to the USA after NAFTA. Caribbean Basin Initiative (CBI) imports from these countries will increase greatly in the future. In a similar move, Europe is also shifting more US Apparel Imports by Market Share based on SME textile imports away from Asia to Eastern Mexico European and North African countries. CBI* 20 The much-discussed WTO will have little effect China on tariffs compared to regional agreements. 15 Hong Kong Under the WTO agreement the US import duty % 10 Bangladesh on a pair of cotton pants, for example, will 5 Taiw an Philippines decline from 17.7 % today to 16.6 % in 2004. In 0 1994 1997 1999 Indonesia contrast, under the NAFTA agreement the import Canada duties on most textiles from Mexico and Canada are already at or near zero. Figure 2. Mexico and CBI countries are replacing Asian As a result of such measures, textile imports apparel imports. from Mexico have grown from 50 % of the level of imports from China in 1994 to now 200 % of China VSF Fabric Exports to Africa the imports from China in 1999. Apparel imports from Mexico and the CBI nations have grown 15000 from 16 % in 1994 to 33 % of all imports in 10000 1999. China, on the other hand, has dropped Benin from 11 % in 1994 to 6.6 % in 1999. MT Africa Total The resulting shift in regional trade will have a 5000 staggering impact on Asian textile exports. The 0 USA and Europe are by far the largest importers 1997 1998 1999 2000 2001 of textiles. Asian producers have always assumed that their cost advantages will allow Figure 3. Sub-Sahara Africa becomes new player in VSF them to continue their export growth to these textile trade. 7

Risks of export dependency Yarn Cost Comparison Storage, interest, 1% The focus on textile exports has left Asian textile $0.80 producers vulnerable. Exporters are open to a Duty , 8.5% $0.60 number of risks compared to those selling in Transport Costs, their domestic markets. The added costs of $0.40 CNF Europe $/kg Capital Cost $/kg transportation, duties, transaction costs, storage $0.20 costs and distance to the customer can be higher Electricity Cost $/kg than advantages in labor or other costs. $0.00 USA Indonesia Labor Cost $/kg A variable cost comparison between a European viscose yarn spinner and an Indonesian spinner Figure 4. Yarn production cost comparison. shows that the Indonesian producer has a $0.31/kg advantage (Figure 4). After adding The viscose yarn imports by the major importing capital costs, where developing nations, such as countries have been growing on average by 4% Indonesia, are at a disadvantage, the difference annually. On the other hand, Indonesian viscose has reduced to $0.20/kg. After adding yarn exports grew by 26% in 1999 and 10% in transportation, duties and storage costs, the 2000 (Figure 5). This imbalance implies that the difference changes to $0.13/kg to the advantage rapid growth in exports can only be maintained of the European spinner. Currency fluctuations through aggressive growth in market share. This can also greatly influence any cost advantage a is becoming increasingly difficult as Indian yarn producer might enjoy. Finally, since higher-value exports are growing rapidly due to the export items tend to be short-lived, most imports are subsidies given by the Indian government to yarn limited to easy to forecast commodity items, exporters. In addition, Indonesia has already where margins are low to begin with. become the major supplier to most of the major Another risk of export dependence is the markets, putting Indonesian spinners on the exposure to changes in foreign government defensive rather than offensive. policies. Duties, quotas, export subsidies and other trade policy instruments can change the Indonesian Viscose Yarn and Fabric Exports playing field overnight. The inequalities created by these policies can be very significant and 50 difficult to overcome with production cost 40 advantages. 30 YARN EXPORTS 20 FABRICEXPORTS 10 Status of Indonesian viscose yarn and fabric 0 exports

The Indonesian viscose industry is very Figure 5. Indonesian VSF yarn exports have continued to dependent upon yarn and fabric exports. grow, but fabric exports have declined dramatically. Applying the information gained about global textile trade trends, we will look at the risks and After a sharp drop from 1995 to 1997, viscose opportunities for the Indonesian viscose yarn and fabric imports by the major importing countries fabric producers (Figures 6-12). have remained flat. Indonesian weavers have lost Since 1990, viscose yarn exports from Indonesia market share in most of the major markets. In the have increased sharply. Up until 1995, viscose UK, for example, imports from Indonesia have fabric exports exceeded yarn exports on a declined from 6.400 MT in 1995 to 1.200 MT in volume basis. In 1995, viscose fabric exports 2000 while imports from Taiwan have grown started to decline while yarn exports continued to from 2.300 MT in 1997 to 5.000 MT in 2000. grow. This change in trends was a result of Thailand is another major importer of viscose expansions in spinning capacity with new fabrics. China has constantly maintained a equipment, enabling yarn producers to compete market share of over 85 % over the past 5 years in European and other high-quality markets. while imports from Indonesia have declined from 4%to2%inthesameperiod. 8

Imports of VSF yarns in major markets VSF Yarn Imports into Korea

90 25 80 70 20 USA Others 60 Japan 15 Thailand 50 S. Ko rea 40 Gr eece India

Italy '000 MT 10 30 China Belgium 20 5 Indonesia 10 0 0 1995 1996 1997 1998 1999 2000 2001 1995 1996 1997 1998 1999 2000 2001

Figure 6. Minimal growth in major VSF yarn importing Figure 9. Indonesia has increased its market share of VSF markets. yarns imported into Korea from 23 % in 1995 to 63 % in 2001.

30 Imports of MajorVSF fabric importers 180 20 160 Belgium 140 10 Italy UK 120 Greece China S. Korea 100 0 Japan 80 Korea

$0 .0 0 $0 .05 $0 .1 0 $0.1 5 $0 .2 0 $0.2 5 '000 MT USA 60 USA -10 40 Thailand 20 -20 0 1995 1996 1997 1998 1999 2000 2001 Y arn M argin $/ kg

Figure 7. Yarn market analysis. Figure 10. Stagnation in major VSF fabric import markets.

VSF Yarn Imports Italy Market Share VSF Fabric Imports UK

100% 20 18 Others 80% Others 16 India 60% Thailand 14 China S.Korea 40% India 12 Indonesia 10 Indonesia 20%

'000 MT 8 Turkey 0% 6 Taiwan 4 2 0 Figure 8. Indonesia is losing share in Italy. 1995 1996 1997 1998 1999 2000 2001 Figure 11. Indonesia has lost market share in the UK VSF fabric market, from 36 % in 1995 to 11 % in 2001. 9

Thailand VSF Fabric Imports The Indonesian government supports most textile producers with low import duties on raw 30 Others materials. In the ASEAN markets, Indonesian 25 EU producers also enjoy duty advantages compared 20 Taiwan to other countries outside the trade zone. 15 Korea

'000 MT 10 Japan 5 Indonesia Business system and reputation advantages 0 Hongkong 1995 1996 1997 1998 1999 2000 2001 China Indonesian yarns are able to match the quality levels in Europe and USA. Fabrics, however, are Figure 12. VSF fabric imports into Thailand are mainly deemed suitable for printing. The fact dominated by China. that over 90 % of fabric exports are greige fabrics indicates that Indonesian dyeing and finishing capacities need to be improved to Strategies for the future become more competitive in the global markets. In order to be successful in the future, Indonesian Extremely low labor costs and subsidized power viscose yarn and fabric producers will have to costs provide Indonesian producers with an look for new areas of sustainable competitive advantage in variable manufacturing costs. Yarn advantage. With the past paradigms changing spinning equipment is usually world-class and rapidly due to regional trade blocks, they will relatively new. Shuttle weaving capacity is large have to systematically look for new strategies by and low-cost but air-jet weaving is proving to be looking at structural advantages, strengths in increasingly uncompetitive. brands or reputation, business system In the field of product marketing, the Indonesian advantages, internal skills and where their producers depend to a high degree upon traders competitors are facing constraints. in export markets. In contrast, a strong network of close supplier-customer relationships supports sales in the local market. The product focus in Structural advantages Indonesia is mainly on commodity yarns and fabrics, which are easy to sell. The limited Indonesian spinning and weaving mills are development of new products by Indonesian usually outfitted with +30.000 spindles and +100 producers is due mainly to their past focus on looms (A.J.) or +600 shuttle. Advantages economies of scale as a competitive advantage. stemming from the economies of scale are limited due to the modular structure of the equipment. Any reduction in fixed costs will be Constraints on competitors marginal with the addition of more equipment since the major overheads are linked to the The Indian export subsidies on viscose yarns interest and depreciation on the invested capital. have helped them penetrate the European and The high concentration of spinning and weaving Korean markets. This is actually a constraint on mills in Central and West Java give companies Indonesian spinners. There is hope that Europe the advantage of low transportation costs and will impose anti-dumping duties on imported close relationships with their customers. yarn, which should not affect Indonesian Conversely, in export markets, Indonesian spinners. exporters are handicapped by the relatively high Turkey recently imposed anti-dumping duties on freight costs compared to other Asian countries. Chinese viscose fabrics. This has created an With 3 modern viscose fiber plants in Indonesia, opportunity for Indonesian weavers if they can there is ample supply of high-quality viscose adapt to the constructions and fabric widths fibers to support the downstream industries. This needed in the market. is reflected in the relatively high consumption of Taiwanese viscose fabric producers are strong in viscose fibers in Indonesia, 12 %, vs. the world innovation but the industry is shrinking. Luring average of 4 %. Taiwanese fabric finishers to Indonesia should be 10 a top priority. This will bring the technology yarns are becoming threats to Indonesian yarn needed to improve the competitiveness of exporters in key markets like Italy and Korea. Indonesian viscose fabrics. There is some potential for VSF fabric exports Indonesia remains at a large disadvantage from Indonesia. The strategy must utilize the compared to other Asian countries with respect competitiveness of the shuttle loom capacity in to viscose yarn and fabric exports to the USA. Central Java as well as develop more This is due to the small quotas available to sophisticated fabric finishing capacity to Indonesian producers. More lobbying needs to be compete with Turkey and Taiwan. More focus done to gain equal access considering the size of must also be given to the Indonesian, Asian and the Indonesian viscose textile industry. non-quota markets for textiles. In the future, local and regional markets will give better margins and more stability to Indonesian Conclusions producers as regional trade pacts make exports less attractive. The USA and Europe are switching their garment and textile sourcing to regional suppliers. This will make continued growth in exports from Asia more difficult. Indonesian VSF yarn exports are still growing at a faster rate than the total import market. Indian and Thai 11

CELLULOSE IS MUCH MORE THAN A CHEMICAL

Wilhelm Albrecht Akzo Nobel Faser AG, P.O. Box 100149, Kasinostr. 19-21, D – Wuppertal, Germany

Cellulose is the basic substance of life. It is the this planet – it is an ideal substance for product of a constant circuit comprising materials for human use. water, carbon dioxide and energy. And for this reason alone – as long as there is life on Keywords: cellulose, viscose process, fibers ______

Cellulose occurs – as one might expect from capacity and dyeing behavior. Moreover, for a nature – more or less in association with other long time substances have been added to viscose, substances and in a non-uniform appearance. which convey special properties to the fibers, e. This is acceptable for a lot of applications, but g., a more or less pronounced brightness, color, not for modern chemistry, which requires flame-retardation, an X-ray contrasting effect, chemicals to be used as pure and as uniform as changes in the dyeing behavior and special possible. For this reason it was a happy adsorption properties for hygiene and medical circumstance that cotton linters were used to applications. When it comes to additives, viscose develop „artificial silk“ according to the Nitro offers a wide range of possibilities since there are and Cupro processes. In the viscose process lots of interesting substances for the market, introduced later for the production of cellulosic which resist alkaline and acidic production man-made fibers of wooden pulp, the rules of conditions. A high temperature resistance - as chemistry, today considered a matter of course – with the production of melt-spun fibers - is not i.e. the purity and uniformity of the chemicals necessary. used–wereelaboratedstepbystep.This included determining limit values for impurities To sum up it, can be stated that the viscose and agreements regarding the average rate of process offers lots of interesting possibilities. It polymerization of pulp (DP), whereby is, however, necessary to solve the ecological incidentally the DP is only a nominal size, which and economic problems, which are already cannot be recorded with any degree of important today and will gain importance. In this exactitude. Likewise the condition of the pulp – field Lenzing has – in my opinion successfully - sheets, rolls or pulverized – was determined as conducted admirable research and development far as possible by a whole series of test processes work and developed solutions which are within relatively narrow limits. In this way it was futuristic. possible and it still is possible to optimize the procedure without reaching the reactivity of the cellulose, which the existing hydroxyl groups So what is it all about now? lead us to expect. Also additives help only marginally to influence the reaction process. In the course of the last decades the work carried Generally, it is still the case that chemical ourinanuninterruptedfashiontosolvethose implementations in the viscose process are both problems, which still exist with regard to the time-consuming and problematic. production of viscose fibers – unquestionably smaller but still around –, has furnished a wealth With regard to regenerating the cellulose in fiber of practical experience since it was possible to form, on the other hand, lots of progress has been compare the derivative process with the solvent made in terms of designing the fiber properties – process in big scale production. In this respect it such as the titer, cross-section, fiber surface, has been seen – and that is state of the art of crimping, tenacity, elongation, performance engineering – that both of these processes and 12 their products have disadvantages and particle counts in the viscose alleviate advantages. If one concentrates on what is filtration and improve the spinning behavior. decisive, then the viscose process has the • By adapting the spin baths and the after- advantage of being able to produce a whole treatment, the properties desired can be range of fiber types, which can largely be obtained for standard fibers. processed in their respective applications without • A reduction in the operating time for the any difficulty and turned into valuable finished pulp used is possible. articles. In line with our knowledge to date this is • Moreover, it can be seen that the potential also true of other derivative processes. for improvement, when compared with the These processes also force us to „come to terms“ classical procedure, has not been exhausted with the „derivation agents“, which is not so easy so far. and presents a number of special problems in the viscose process. In addition, the derivative Therefore, the results worked out point all in the solution contains a relatively small amount of right direction: an improvement in the ecological cellulose so that relatively large volumes have to and economic aspects of the viscose process. be moved, tempered and cleaned, which takes a The facts illustrated do not just demand further lot of effort, and influences the regeneration development, but also require research to fully process of the cellulose from the viscose clarify what interrelations there are to allow a solutions. universal application, and perhaps even to On balance, viscose is an interesting fiber for the determine what the effects of this might be. textile world – producing it, however, involves a All that remains is to consider whether the number of problems from an economic and regeneration of viscose - as was common until ecological point of view. now - will take place in the future from the bottom to the top, or - as in the case of the Cupro process - from the top down. This would avoid What has to be done? the „bathing trunks battle“, which limits the spinning speed. This is a technical problem The realization that the number of hydroxyl which can be solved relatively simply with the groups in the cellulose molecule allows us to knowledge available. expect a higher reactivity than was observed encourages chemists to make these hydroxyl To summarize, it can be said that the viscose groups more accessible – to “activate” them, process still has a great deal of potential for whatever that might mean. As a result the improvement. In the truest sense of the meaning reaction speed will increase and will probably be it would, therefore, appear to be beneficial to less problematic, producing a series of make use of the approaches already established consequences for the process. and find answers to the questions already Is this only wishful thinking or are there still formulated which are as follows: some possible ways of „activating“ the cellulose • to activate the reaction ability of the molecule? We know of course that the irradiation cellulose, of eucalyptus pulp of one manufacturer with • to increase the spinning speed, and electrons represents a good approach, which is • to continue closing off production towards a worthwhile to follow. Even if there is still no closed circuit process. unanimous opinion about the causes of the effects determined and the transfer of this to other types of pulp, this procedure is too Solvent processes promising not to be paid further attention to. What have previous tests revealed in A general reflection of the situation leads us to unambiguous terms: the conclusion that the regeneration of cellulose • The amount of NaOH and CS2 used can be from derivatives must contain more chemical and reduced and the cellulose concentration in technical possibilities to control the process than the viscose can be increased. The low a solvent process. Nevertheless, the question arises whether there are other plausible ways, in 13 which the targeted goal can be more easily customer’s satisfaction within a few days, at reached than done to date, i.e. the production of most 2 – 3 weeks. There is not longer a need to fibers without the tendency to fibrillate. This prove that this can be accomplished with the would make it possible to considerably extend proper organization and necessary machinery the application range of Lyocell fibers, however adaptations. LENZING SXS-Technik is here an without obtaining the variety of viscose fiber excellent example. We can add the companies’ types. willingness to produce large quantities. Even the To sum up, it can be said with certainty that subject of the „cost“ and passing this on to the solvent processes also have development customer within the textile pipeline can be potential; however, the fibers produced solved: the simplest way is naturally in textile according to these processes cannot be so readily companies, which have all phases of the textile modified as we are used to do with those from process. the viscose process. However, since cellulose is It goes without saying that spin dyeing is available practically in unlimited quantities and a unlikely to replace classical dyeing in the fashion rising quantity of fibers is needed, it is worth area – that is, moreover, certainly not the goal – making a research effort in both fields – the but it can, where this is desired, raise the color derivative and the solvent processes. fastness levels of textiles to a higher level. This applies for example to cotton textiles with which these kinds of spun-dyed viscose fibers are Are there other tasks for R&D in the field of blended. cellulosic man-made fibers? The fact that the manufacturer of special fibers, when signing large-scale contracts on natural I think so; they are developing along with the white, has normally good opportunities is of market and with the increasing importance of course a beneficial side effect of the effort he has ecology – even for fiber products and their undertaken – with which money can, as such, be applications. earned. The fact that the equipment needed for On the one hand, the market place is demanding this can also be used to produce special fibers large quantities of fibers of one type and on the needs not be given any particular mention. other hand smaller to small quantities of I see another task for the engineer trying to specialty fibers. In my opinion development develop applications for cellulosic man-made work did justice to the large lots of the past fibers in the field of spun-bond materials where it decades in an excellent manner. Today the is desirable to use degradable fibers when productivity of the plants has reached an producing various hygiene and medical textiles. impressive level and still appears to have What happens to these after their use would then potential for further increase. no longer represent a problem. Naturally, more On the other hand, I believe that the development lightweight spun-bond materials of cellulosic work in smaller, but more flexible plants has man-made fibers would be a new addition to the been left behind. There is a demand for it in the market. They do, however, involve problems, market, which will grow since classical dyeing even though their advantage – the degradability – and finishing of textiles is increasingly running would seem to guarantee real chances, into problems, which include the environment particularly since they can also be suitably and the cost and fastness values, to name but a modified. few. However, solving this task will not merely mean At the end of this paper, let us come back to a developing flexible spinning machines for small dream of all cellulose chemists, namely to quantities, but also a system that organizes the increase the maximum tensile strength even use of the right additives in accordance with their further. If one evaluates the pertinent tests type and quantity. In most cases it certainly carried out to date to produce extremely strong makes no sense to spin special fibers to be kept fibers from cellulose, then one finds no clear in stock or to let customers wait for weeks on an approach, particularly if one also adds synthetic order being fulfilled. An order, e. g. about a fibers and the possible costs of production to spun-dyed type, has to be dealt with to the these considerations. What would, however, 14 happen, if we transferred the wide-ranging before the regeneration of the fibers like other knowledge we have concerning composites to additives. The only logical thing to do is to fibers? Today it is natural to use molecules with extend this idea to short fibers of cellulose and the longest chains possible to produce high- other polymers. This would pave the way to two- strength fibers and to orientate these in the fiber component fibers with a cellulose matrix direction as well as one can. To this end, whereby the cellulose would guarantee the good corresponding starting substances are used. With adherence to other substances for which it is all kinds of composites, fiber-reinforced plastics, known. This is undoubtedly a vision but it is not the matrix and the reinforcement fibers are not utopia – a thought that shows what cellulose joined together until the composites are “still has to offer”. produced. If this production process is It is up to us to develop ideas, to examine these transferred to the production of fibers then the and turn them into reality. He, who rests, is lost. long-chain molecules – for the reinforcement of individual fibers – should only be added shortly 15

 VISCOSTAR - A STAR-SHAPED VISCOSE FIBER FOR IMPROVED ABSORBENCY

Josef Schmidtbauer Lenzing R & D, Lenzing AG, A-4860 Lenzing, Austria Phone : +43 7672 701 2387, Fax : +43 7672 918 2387, e-mail: [email protected]

For many absorbent nonwoven products, syngina absorbency, the geometry of the fiber such as tampons, viscose is the dominating cross section had to be defined and a spinneret cellulosic fiber. As tampon manufacturers had to be designed providing good spinnability, aim at continuously improving the a consistent shape of the fiber cross section and performance of their products, a new high spinneret lifetime. For the first time a approach was taken to develop a viscose computer-aided simulation of the fluid fiber especially designed for this particular dynamics in viscose fiber spinning was used to end-use. The traditional parameters used to support the spinneret design process. measure the absorbency of fibers (water By a systematic investigation of the influence of retention and imbibition) turned out to be certain process parameters on tampon insufficient to characterize the absorbency of absorbency, the performance profile of tampons. Novel lab methods for Viscostar® - the new star-shaped viscose fiber - manufacturing and testing of tampon-shaped was optimized. Upscaling from pilot plant scale plugs had to be introduced and syngina into commercial production has been absorbency was selected as the lead successfully completed. Viscostar® is a totally parameter for fiber development. chlorine free viscose fiber, which meets the In a comparative study, a viscose fiber with a highest product safety standards and improves trilobal cross section seemed to be the best the absorbency of traditional tampons from option. In order to achieve maximum viscose/cotton-blends significantly. ______

Introduction Profiled viscose fibers and filaments have already been known for many years, so this Viscostar® is a viscose fiber with a star-shaped paper will not deal so much with the fiber itself, cross section, which was designed to improve the but concentrate on the new approaches, which absorbency of nonwoven products, especially of have been taken to better understand the tampons. interactions between production parameters and fiber properties on the one hand and performance, especially absorbency of the final product, on the other hand, and will present some new tools and models which had to be developed for this purpose. Unlike in textile applications, viscose is the dominating cellulosic fiber in nonwovens, because of its superiority in absorbency and purity and the tailor-made physical properties. Nonwovens are a rather stable and constantly growing market, and one of the most sensitive nonwoven products are tampons. Today, about 75% of the fibers used for tampons worldwide are already viscose fibers, and cotton is going to Cross section of Viscostar®. be phased out. 16

Like most other manufacturers of consumer achieve maximum tampon absorbency. In order goods, tampon producers are continuously to find an answer, prototype fibers with a wide improving their products by either increasing the variation in absorbent properties were performance or reducing costs of their products manufactured and processed into tampons, thus or even both. For tampons, this means to achieve investigating the correlation between fiber higher absorbency with the same amount of fiber absorbency and tampon absorbency. The range or to maintain a certain level of absorbency with for water retention of the prototype fibers less fiber material, thus improving comfort and investigated in this study was between 40 to reducing costs. 140%, for water imbibition between 21 to 28 g/g. In response to the needs of tampon Looking at the outcome of this exercise, we manufacturers, Lenzing R&D started a research found that the correlation between water project to develop tailor-made tampon fibers imbibition of the fibers and tampon absorbency with improved absorbency. was extremely poor. Fibers with a high water The first approach was quite simple: if you want imbibition value, such as cotton or a physically to have a tampon with improved absorbency, you modified viscose fiber codenamed “Hydrophil have to take a fiber with improved absorbency. B”, performed less well than the trilobal fiber We started to explore the technical feasibility of Viscose TC or a chemically modified viscose making absorbent fibers by various physical and fiber containing guaran, which was called chemical modifications and to investigate the “Hydrophil G” (Figure 2). performance of such fibers in tampons, see 19 Figure 1. 18 Viscose TC 17 Physical Incorporation of Hydrophil G 16 Modification Absorbent Polymers Hydrophil B 15 Viscose 14 13 Cotton

Carboxymethyl cellulose syngina12 absorbency [g] Microfibers Cellulose carbamate 11 Profiled fibers Starch 19 21 23 25 27 29 Super crimped Alginate water imbibition [g/g] fibers Guaran Hollow fibers Figure 2.

The correlation for the water retention value Figure 1. looks better, but a significant increase in water retention did not lead to an improvement in tampon absorbency as can be seen by Absorbency of fibers comparison of Hydrophil G and Viscose TC (Figure 3). The parameters traditionally used to characterize the absorbency of cellulosic fibers are water 19 retention and water imbibition. 18 Viscose TC 1 17 While water retention measures the amount of Hydrophil G liquid retained by swelling inside the fiber after 16 Hydrophil B removing the excess liquid in a centrifuge, water 15 Viscose imbibition2 measures the water holding capacity 14 of a loose bundle of fibers under gravitational 13 forces. syngina absorbency [g] 12 Cotton A major question was, which of these parameters 11 should be selected as the lead parameter to 30 50 70 90 110 130 150 water retention [%]

1 determined according to DIN 53814 Figure 3. 2 determined according to European Pharmacopoeia 4 01/2002:0034 17

Parameter Lenzing ERT 350.0-02

Test fluid: deionised water 10 g/l NaCl soln. 0.5g/lacidfuchsin Tampon Position of Syngina vertical 30° to vertical chamber: Hydrostatic Pressure: 180 mm 180 +/-10 mm Temperature: room temp. 27 °C Addition of fluid: 25 ml at once 50 ml/ hr End point: after 3 min. leakage

Table 1.

So the conclusion was, that none of the which forced us to develop a new technology to parameters used to characterize fiber absorbency the extent necessary for a production run. was suitable as the lead parameter to maximize Under these circumstances, a complete tampon absorbency and that a fiber with trilobal development cycle with a new fiber took 6-12 cross section seemed to be the best choice. It also months, and this was unacceptable for an showed, that other - at that time unidentified - efficient R&D work. Consequently, there was a parameters than fiber absorbency have a clear demand to turn the wheel of innovation significant influence on tampon absorbency and much faster. that we had to take the absorbency of the final A lab method was developed for processing a product as the lead parameter for our fiber certain amount of staple fiber into a card sliver, developments. compacting and rolling the sliver to form a cylinder, putting the sample into a mechanical Tampon absorbency press, forming a plug with the same shape, volume and fiber orientation as a digital tampon Tampon absorbency is measured by application and measuring the absorbency of the plug in a of the so called Syngina Test. The absorbency of SynginaTest(Figure4). a tampon is tested under simulated „real-life“ With this equipment it was possible to reduce conditions at a certain hydrostatic pressure. cycle time down to a few days and it was easy to As no international standard was available at that get a quick feedback from small fiber samples. time we developed our own Syngina Test. In the By comparison of results obtained from plugs meantime a European standard test has been and commercial tampons, which were issued by Edana3. The Lenzing Syngina Test, is a manufactured from the same fiber materials, we simplified version of this Edana test, see Table 1. were able to validate our method and to confirm At that stage of development we had available the good correlation. the tools to manufacture new fibers in pilot plant Now all the necessary prerequisites were in place stage and to assess the absorbency of tampons. for an efficient design of a tailor-made tampon However, we were not able to process small fiber, and we were ready to start our Viscostar® quantities of fibers into tampons for testing project. Syngina absorbency. Inordertodothisincooperationwithtampon manufacturers, at least 30 kg of fiber were necessary, and in order to provide 30 kg of fiber material we had to run a short production trial,

3 ERT 350.0-02 18

Compacted card sliver Stable fiber

Tampon-shaped plug

Mechanical Tampon Press

Syngina Test

Figure 4.

Hole design : shape of orifice shape of viscose flow channel length of capillary

Number of holes Distribution of holes

Orientation of holes

Figure 5.

The Viscostar® Project Compared to traditional spinnerets with circular holes, profiled spinnerets have much more Spinneret design design parameters. The length-to-width ratio of the limbs of the The heart of the process for making trilobal spinneret is of critical importance for the aspect fibers is the spinneret. The design of a trilobal ratio of the limbs of the fiber, but also the shape spinneret had to take into account: of the viscose flow channel and the length of the capillary have an influence on the fiber • a well-shaped and consistent fiber cross cross section. The number of the holes per unit section area, their distribution and their orientation • good spinnability and high productivity towards the radial flow of the spin bath are • low sensitivity to process variations important for spinnability and productivity of • and high spinneret lifetime without clogging the trilobal spinneret (Figure 5). 19

Together with an Austrian university, a model distance of 11 mm from the surface. The lower for computer simulation of the viscose flow zone shows the drop in acid concentration in inside the spinneret was developed. In diagram the center of the spinneret. Computer 1 different flow rates in a section of the trilobal simulation gave us a much better understanding spinneret are visualized by a grey-scale code. of the critical design parameters of a spinneret, Weobserveahighflowrateintheinnerzone, but the theoretical results had to be validated by whereas the outer zone with a low viscose flow spinning trials on our pilot plant. rate is critical with regard to coagulation and partial clogging. Pilot plant spinning trials

The viscose pilot plant of Lenzing R&D, manufactured by Lenzing Technik is designed for spinning of about 1 kg viscose fibers per day. The modular equipment is downscaled from industrial installations and furnished with the same type of process control system. About 20 different spinneret designs were tested in this pilot plant. Small variations of the aspect ratio of a trilobal spinneret can have a significant influence on the shape of the fiber Diagram 1. cross-section and also on syngina absorbency. Experience with circular hole spinnerets shows, Our spinneret design targeted achieving a good that a certain hole diameter of e.g. 90 my is uniformity of the viscose flow, but for a stable suitable for spinning of fibers in the range from spinning process uniform spin bath flow and 2,8 to 5,6 dtex without any significant influence acid distribution are also most important. on fiber properties. Trilobal spinnerets however So a computer model was developed, which can only be used in a relatively narrow window allowed us to combine the chemistry of the of titer. Outside this window the shape of the regeneration process with the fluid dynamics of cross section changes significantly. wet spinning and enabled us to simulate the Once the decision for a certain design of the acid distribution across the spinneret surface for trilobal spinneret had been made, the process various designs. conditions had to be optimized to achieve maximum syngina absorbency. In order to reduce the number of trials, experimental design with a limited number of parameters was used (Figure 6). Surprisingly, the type of pulp can have a significant influence on syngina absorbency: prehydrolized kraft pulps seem to perform Diagram 2. better than sulphite pulps (Figure 7). The addition of a viscose modifier, e.g. PEG 1500 has a positive influence on syngina absorbency (Figure 8). Scaling up from pilot plant to bulk production was performed step by step. Depending on pulp quality, absorbency slightly declines with increase of production speed (Figure 9). Diagram 3. Finally, in a 110-hours production run it could be proved, that Viscostar can be produced in Diagram 2 shows the acid distribution very consistent quality without a frequent change of close to the spinneret surface, diagram 3 in a spinnerets. 20

The following parameters were investigated in order to achieve maximum syngina absorbency • Pulp Estimated Response Surface • Viscose composition & quality 20 • Type and amount of modifier 19 Syngina18 • Spinbath composition 17 16 380 360 • Stretch 340 320 Na2SO4 70 80 90 300 • Spinning speed 100110120130 H2SO4 • Aftertreatment & washing • Type and level of fiber finish Experimental design • Drying temperature Figure 6.

The profile of Viscostar®

20 19,8

19,5 19,5 19 18,8 18,6 19 18,5 pulp T 18,5 18,3 18,2 18,5 pulp S 18 Syngina 18 absorbency 17,5 17,5 syngina absorbency [g/plug] (g/plug) 17 17 123 F /C F m/mi /TC /ECF /EC i/sw w hw S i/ /h /hw S K Si/hw/ECF HK/sw/ECF HK PH P P Figure 9. Absorbency vs. increase of production speed. Figure 7. Si = sulphite; PHK = prehydrolized kraft; hw= hardwood; sw= softwood; ECF= elementary chlorine free; C= chlorine bleached; TCF= totally chlorine free. Compared to regular viscose Viscostar® is characterized by a higher titer, the same staple length and tenacity, a lower elongation, a higher Syngina absorbency [g/plug] 19,5 water imbibition at the same level of water

19 retention, of course a higher Syngina 19 18,8 18,7 absorbency, and a higher bulkiness. The finish 18,5 level is a little bit higher, PEG content is below

18 17,9 the limit of detection, and the fiber is bleached totally chlorine free [tab.2]. 17,5

17 02,53,55 PEG 1500 [%/Cell.]

Figure 8. Effect of adding a viscose modifier. 21

Summary viscose fiber, which meets the highest product safety standards and improves the absorbency What we have experienced in this project is, of traditional tampons from viscose-cotton- that enhanced fiber absorbency does not blends significantly. Compared to tampons necessarily lead to improved tampon made of 100% cotton the absorbency of absorbency. For this reason, the absorbency of Viscostar® tampons is up to 50% higher. the final product - the tampon - and not the absorbency of the fiber was selected as the lead parameter for the development of Viscostar®. Acknowledgement Novel lab methods for manufacturing and testing of tampon-shaped plugs had to be This paper is based on the research work introduced. performed by the Lenzing Viscostar team and I For the first time a computer-aided simulation would like to thank especially my co-workers of the fluid dynamics in viscose fiber spinning Susanna Schiemer, Helmut Weißböck, Heinrich has been used to support the spinneret design Schmidt and Robert Kickinger for their process. Viscostar® is a star-shaped TCF valuable contributions and their excellent work.

titer [dtex] 3.3 +/-0.1 2.8 staple length [mm] 30 30 tenacity cond. [cN/tex] 22 22 elongation cond. [%] 17 21 water imbibition [g/g] 25.5 21.5 water retention [%] 87 85 rel. syngina absorbency [%] 117 100 rel. bulkiness [%] 140 100 finish [% ] (EtOH extr.) 0.06 0.06 PEG [%] n.d. n.d. TCF ü ü Table 2. 22

RAINBOW: A NOVEL VISCOSE FIBER FOR PES BLENDS INNOVATIONS IN DYEING TECHNOLOGY

Peter Sulek, Marina Crnoja-Cosic, Jörg Schlangen Lenzing Aktiengesellschaft, A-4860 Lenzing, Austria Phone: +(43) (7672) 701 3167, Fax: +(43) (701) 918 3167 E-mail: [email protected]

Blends of Viscose and PES are widely used in polymer into the viscose spinning dope, thus the textile industry, but the traditional dyeing achieving permanent modification. Suitable process is complex as a two-step procedure is dyeing procedures have been developed in required. Using the Rainbow fiber, the fabric cooperation with DyStar. By an appropriate can be dyed in a single step at low pH without selection of DyStar direct or metal complex addition of salt requiring only one rinsing step dyes, a light fastness similar to conventional and achieving a very high degree of dye bath viscose has been achieved while all other exhaustion. Thus, dyeing time is reduced by fastness properties remain equivalent to 50-65% giving the dyehouse manager the viscose fibers. opportunity to double or triple productivity. An additional benefit is the reduced Keywords: cationization, viscose fiber, consumption of energy, (waste) water and salt. incorporation, PES-blends, dyeing, one-step This unique combination of properties has been realized by incorporation of a cationic ______

Introduction Inthesameperiodoftimetheproductionof cotton increased about twofold to approximately During the last 50 years worldwide fiber 20 million tons per year, while the cultivated production has increased fivefold to some 52 area remained constant [1]. Higher output has million tons per year due to an increase in been achieved by herbicides, agrochemicals and population and a higher per capita consumption. elaborated irrigation systems. The outmost limit This huge increase could only be covered by of production has been reached by now as synthetic fibers which reached a quantity of cultivated area will most like not be increased [2] about 27 million tons per year with the most or even be reduced due to shortages in water prominent contribution from polyester fibers (19 supply, erosion or the necessity for food million t/a), see Figure 1. production. Cotton plants with higher productivity are also not feasible [3]. Worldwide fibre consumption 2000 (%); total 52 million tons Till 2010 fiber demand will increase even further to some 65 million tons per year due to a

PES population increase and an increase in per capita

PA demand. The above outlined reasons suggest that

PP this demand can only be covered by synthetic

Acryl fibers. But as people opt for fabrics with a high

Other synthetic fibers comfort when wearing and easy handling when

Man Made cellulose washing, polyester-viscose blends can be the

Cotton material of the future.

Other natural Fibers Polyester fibers offer excellent textile properties. Figure 1. Fiber consumption in the year 2000. High tenacity (dry and wet) results in good mechanical properties and durability. Furthermore, polyester shows good dimensional 23 stability at a reasonable price. Problems can be 8 million tons of polyester-viscose blends will be found in wear comfort, as polyester is a processed by the year 2010. hydrophobic fiber and thus cannot control Dyeing of polyester-viscose blends (yarns and humidity. The material feels wet on the skin, fabrics) is a very complex process (Figure 2). which results in a sensation of low comfort. The blend requires a very high input of labor, Polyester microfibers used in sport applications when dark shades are to be dyed at high quality. transport humidity via capillarity, which works The reason can be found in the very different well at high “sweat levels” but has only limited dyeing procedures of both fibers. Polyester is applicability in “normal life”. usually dyed with dispersion dyestuffs at 130 °C Cellulosic fibers, on the contrary, show water and pH 4.5 to 6 while cellulosics are dyed using retention of 40% to 80%, and can thus easily reactive dyes at 60 °C, pH 6 to 10 and a high control humidity. The fiber feels dry and dosage of salt. Here, not covalently bound comfortable on the skin. In combination with the dyestuff has to be removed by soaping and/or soft handle cellulosic fibers offer excellent washing. This requires that the single fibers have wearability. to be dyed one after the other in blends of The profiles of these two fibers suggest that a polyester and viscose. The whole process has a combination of both fibers should result in an duration of 10 to 12 hours, which can become optimum for textile applications. These even longer if corrections have to be made. somewhat theoretical considerations are verified Cellulosics could also be dyed by direct dyes by the market. About 5 million tons of polyester under polyester conditions, which results in fair viscose blends are processed per year, which quality only at light shades. makes this fiber blend the most important on the Lenzing has developed a new cationized viscose market. As we are facing a significantly fiber dubbed “Rainbow”, facilitating the dyeing increased fiber demand, blends of polyester and procedure and drastically reducing time viscose should also increase in quantity, consumption, whereby environmental assuming that the consumer consistently wishes compatibility could be improved significantly. high wear comfort. It can be estimated that about

temperature/time profile PES/CV with disperse and reactive dyes

140

120

100 PES-dyeing reductive cleaning 80 CV-dyeing 60 rinsing hot and temperatur (°C) cold water 40

20

0 0 50 100 150 200 250 300 350 400 450 time (min)

Figure 2. Time / temperature profile of a conventional polyester-viscose blend. 24

Methods performed on a Minolta Spectrophotometer CM- 508/DA. The viscose dope has been cationized by incorporation of a cationic polymer using Results standard laboratory equipment, and has been spun into fibers using a standard pilot spinning Lenzing intended to develop a viscose fiber, line. Fiber after-treatment has been done at which can be dyed under polyester conditions, laboratory scale. Samples have been dyed using thus significantly reducing dyeing time of Mathis laboratory equipment. Fastness properties polyester-viscose blends. This fiber development have been tested according to international has been named “Rainbow”. In Figure 3, the standards. Colorimetric measurements have been potential timesavings are indicated.

temperature/time profile PES/CV with disperse and reactive dyes

140

120

100 PES-dyeing reductive cleaning 80 CV-dyeing 60 rinsing hot and temperatur (°C) cold water 40

20

0 0 50 100 150 200 250 300 350 400 450 time (min)

Figure 3. Time / temperature profile of a Rainbow polyester blend.

This ambitious goal has been reached by Rainbow + cationization of the viscose dope before fiber spinning. A cationic polymer has been + + + + + incorporated in the viscose spinning dope and the ++ + fiber has been spun by a standard viscose + + + + Charge within + + + spinning process. As the cationic polymer is + the fibre + incorporated into the fiber, cationization is + + permanent, thus cationic charge cannot be Cationized viscose fibre washed off during textile processing. Usual textile processes or reducing and oxidizing agents do not affect the charge, there are no Figure 4. Cationization in the Rainbow fiber. limitations at elevated temperatures (e.g., 180°C for 60 s), and cationic charge is constant over a Rainbow fibers have the same physical fiber wide pH range (pH 5-13). properties (tenacity, water retention, etc.) as The cationic charge is distributed homogenously usual viscose fibers, except dyeing properties. over the diameter of the fiber. Thus, no excess Rainbow fibers can be dyed at 130°C using charge at the surface can be observed resulting in direct and metal complex dyes without addition a very even color distribution during the dyeing of salt giving fastness properties comparable to process. Looking at fibers cationized during fiber reactive dyeing at 60°C. after-treatment, bad leveling can be observed. Figure 4 shows the cationized Rainbow fiber. 25

Color depth has been measured by colorimetric observed with the Rainbow fiber especially with methods (CIELAB; L-values). It was shown that red shades. This drawback has been solved by an Rainbow has the same color depth as viscose appropriate selection of dyes. A variety of dyed with the double amount of dyestuff or even different direct and metal complex dyes is more. Details can be seen in the in the upper part suitable for Rainbow. In collaboration with of Table 1 (Sirius blue K-CFN and Sirius blue K- DyStar an optimal collection of dyes has been CFN). Even at these much higher color depths selected and tested intensively. These dyes meet reached by Rainbow a better wash fastness has the requirement of a light fastness of 4 or higher. been observed. It follows that dye bath Only red shades, like in the case of standard exhaustion is also significantly improved. viscose, have a slightly lower light fastness of 3- Depending on the dye and intended color depth 4, but there are also examples of red dyestuffs dye bath exhaustions between 92 % and 99% with a light fastness of 4. The selection of dyes have been observed. These trends are shown in comprises both direct dyes and metal complex the upper part of Table 1. dyes; some examples are listed in Table 1. Cationic fibers generally tend to show reduced light fastness. This problem could also be

Fastness to wash fastness 3 light- CIELAB ∆L rubbing 3 fast- ness 3 dry wet color bleed bleed WO 0,5% 1,0% 2,0% CV 1 1 1 Sirius blue K-CFN; 4-5 2-3 4 4 4-5 3 27.5 19.4 13.7 Rainbow Sirius blue K-CFN; 4-5 2-3 3 2 4 7 38.4 29.5 22.5 Standard viscose 2 Sirius brown 3RL; 4-5 3 4 3 3 3 44.7 35.3 28.4 Rainbow Sirius brown 3RL; 4-5 3 3-5 3 3 5 58.7 49.8 41.4 Standard viscose 2 Isolan marine S-RL 4-5 3.5 4-5 4.5 4.5 4.5 - - - Isolan yellow K-PRL 4-5444-54 6 --- 200% Isolan bordo R 220% 4-534 4 3 4 --- Isolan grey K-PBL 4-5344-53 6 --- 200% 1 Concentration of dyestuff 2 Standard Viscose dyed at 130° with salt (0,5% dyestuff and 10g/l salt; 1,0% dyestuff and 15g/l salt; 2,0% dyestuff and 20g/l salt); Rainbow dyed without salt! 3 Fastness properties refer to trials with 1,0% dyestuff concentration

Table 1. Fastness data and color depth at different dyestuff concentrations of various dyes.

Intensive dyeing trials have shown that It can be seen that an enormous decrease in polyester-viscose blends can be dyed at polyester dyeing time results. Up to 70% of the time conditions at 130°C, pH 5,5 without salt in a formerly needed can be saved. If the dyehouse one-bath one-step procedure. Promising results manager can use this additional time have been achieved with both system-blends and productively, the efficiency or productivity of the intimate-blends. Figure 5 shows the dye time- dyehouse will increase by the same amount. This temperature profile and the timesavings of the should improve the cost structure of the Rainbow dyeing process. dyehouse significantly, and should help in the every-day dyeing business. 26

temperature/time profile PES/Rainbow with disperse and direct dyes

140

120

100

PES/CV-dyeing 80

60 temperatur (°C)

40 rinsing

20

0 0 50 100 150 200 250 300 350 400 450 time (min)

Figure 5. The Rainbow dying process.

A spin-off of the Rainbow dyeing process is the in a single step, and dyed fabrics are fully leveled significantly improved environmental situation. and achieve fastness properties comparable to As the whole dyeing procedure is much shorter standard viscose. Rainbow is dyed under water consumption and thus wastewater is polyester conditions (130 °C, pH 5-6) using reduced by 65%. In the Rainbow dyeing process direct or metal complex dyes. By an appropriate no addition of salt is needed therefore no salt will selection of dyes, performed by DyStar, light be in the wastewater. Together with the fact that fastness properties equivalent to standard viscose dye bath exhaustion is much higher than dyed with reactive dyes were achieved. compared to the conventional process with Further advantages of Rainbow are the reduced reactive dyes wastewater is also less colored water and wastewater quantities (by 65 %) and which helps to reduce costs concerning reduced energy costs (by 65 %) per kilogram of wastewater treatment. Because of the shorter dyed fabric. There is no salt, and because of process duration energy costs are also reduce by higher dye bath exhaustion and thus lower up to 65%. amounts of required dyestuff the amounts of dyestuff in the wastewater are reduced. The laboratory development of Rainbow is finished; Conclusion scale-up of the production line is currently performed. Various trials have proved that the Today, polyester-viscose blends are very theoretical improvements can be achieved in the important on the market, and this position will dyehouse. Now, additional tests have been become even more prominent when it comes to started before the introduction of the Rainbow satisfying the growing demand for textiles, since fiber. this blend combines the positive properties of both fibers exemplarily. Unfortunately, the dyeing process is very time consuming and References complex. A two-bath exhaustion procedure with dispersion and reactive dyes, each followed by [1] Johnson, T. Chem. Fibers Int. 2000, 8, rinsing steps, has to be used, which increases 24-28. dyeing costs significantly. [2] Whitaker, P.B.F. ITB 2001, 1, 14-16. With Rainbow, a cationized viscose fiber, the [3] Reller, A.; Gerstenberg, J. GAIA 1997, 6 time needed for the dyeing process could be (1), 35-51. reduced by up to 70%. Thus, polyester-viscose blends can be dyed at significantly reduced costs 27

LENZING LYOCELL: POTENTIALE EINER NEUEN FASERGENERATION

Haio Harms

Lenzing AG, A – 4860 Lenzing, Austria e-mail: [email protected]

Ein paar Jahre nach der Inbetriebnahme der für völlig neue Anwendungen - und bei den ersten kommerziellen Produktionsanlagen, in Ansätzen einer Nutzung der Lyocell- denen die über mehr als ein Jahrzehnt entwi- Technologie für Produkte fernab der bisher ckelte NMMO-Technologie für die Herstel- im Zentrum der Entwicklungsanstrengungen lung von Lyocell-Fasern genutzt wird, beginnt stehenden Fasern, wird immer klarer, dass die sich nun das hohe Potential dieser neuen Ge- direkte Regeneration der Cellulose aus orga- neration cellulosischer Fasern deutlich abzu- nischer Lösung eine neue Dimension bei der zeichnen. Nutzung des hervorragenden Eigenschaftspo- Nachdem der Markteintritt mit den ersten tentials dieses wichtigsten „organischen Kon- Fasertypen vor allem in einzelnen hochpreisi- struktions- und Funktionswerkstoff“ der Na- gen Segmenten gelang, werden nun mit der tur ermöglicht. Marktausweitung deren spezifische Vor- und Lyocell bietet nicht nur die Chance für eine Nachteile in den einzelnen Stufen der textilen neue Generation cellulosischer Fasern - auch Weiterverarbeitung und der Endnutzung für bisher nicht zugängliche Einsatzgebiete, deutlich. Der derart immer besser definierte sondern auch für eine allgemeine Renaissance Entwicklungsbedarf und das zunehmende der Cellulose für unterschiedliche Produkte, Wissen um die Möglichkeiten, das Eigen- bei denen sie entweder in den letzten Jahr- schaftsspektrum zu modifizieren, lassen das zehnten durch vollsynthetische Polymere sub- ursprüngliche Ziel einer neuen, im breitesten stituiert wurde oder bei denen völlig neue Umfang einsetzbaren „Baumwolle–plus“ in Anwendungen für dieses hervorragenden, absehbarere Nähe rücken. natürlichen Polymers erschlossen werden. Aber auch bei der Entwicklung von Lyocell Fasern mit speziellen Funktionalitäten - teils ______

Lassen Sie mich aus gegebenem Anlass1 über die Lenzing-Gruppe im 1. Halbjahr ein umfas- das Thema Lyocell hinausgehend das Potential sendes Investitionsprogramm. Bis Ende 2003 und die Situation von Cellulosefasern etwas ge- werden insgesamt EUR 125 Mio in die Kapazi- nereller behandeln und dabei mit einem kurzen tätserweiterung an den Standorten Lenzing und Zitat aus der jüngsten Presseaussendung der Heiligenkreuz investiert. Die Faserproduktions- Lenzing AG zum letzen Halbjahresergebnis be- kapazitäten in Lenzing werden um 20.000 Ton- ginnen. Da ist unter der Überschrift „Kapazitäts- nen auf 200.000 Jahrestonnen angehoben. ausbau zur Festigung der Weltmarktstellung“ Parallel dazu wird zur Absicherung der folgendes zu lesen: Vollintegration die Zellstoffproduktion um „Um die gestiegene Nachfrage der Kunden im 35.000 Tonnen auf 210.000 Jahrestonnen erhöht Kerngeschäft Fasern optimal bedienen zu kön- werden. Am Standort Heiligenkreuz wird eine nen und Wachstumschancen zu nützen, startete zweite Produktionsstraße die Produktionskapazi- tät auf 40.000 Tonnen jährlich verdoppeln. Mit der Inbetriebnahme der zusätzlichen Kapazitäten 1 Beitrag zum 5. Internationalen Symposium „Alternative ist Ende 2003 zu rechnen.“ Cellulose –Herstellen, Verformen, Eigenschaften“, Rudol- stadt, 4.- 5. Sept. 2002. 28

Soweit die Lenzinger Neuigkeiten vom 29. Au- industrie geführt hat, auch in Europa unaus- gust. Als ich den Titel dieses Vortrages plante, weichlich ist? konnte ich die konkrete Aktualität noch nicht Überraschenderweise hat nicht nur die Cellulose- voraussehen. An vielen Reaktionen ließ sich al- faserproduktion in Europa wieder das Niveau der lerdings ersehen, dass die Nachricht von der ‘80er Jahre erreicht, von denen es heißt, dass Fachwelt doch sehr mit Überraschung aufge- damals „die textile Welt noch in Ordnung war“. nommen wurde. Der Zustand unserer Industrie Auch bei Polyesterfasern hat - trotz der vielen lässt offenbar nur mehr Nachrichten von Be- Schließungen traditioneller Produzenten - eine triebsschließungen erwarten und etliche Vertreter Reihe neuer und kleinerer Spieler für sich Chan- der Branche können nicht verstehen, wie man cen identifiziert und sogar in neue Fabriken in- heutzutage noch neue Faserkapazitäten in West- vestiert (Abb. 1). europa installieren kann. Für Lenzing sind es bereits mehr als 100.000 Jahrestonnen, die in 800 Viscose, Modal, Lyocell weniger als 10 Jahren in Betrieb gehen. Das ist 700 PES staple wesentlich mehr als die kumulierten Schließun- gen anderer Produzenten in derselben Periode. 600 Aber natürlich bleibt die Frage: ist Lenzing eine 500 Ausnahme, oder wären wir besser beraten gewe- 400 sen, dem Trend zu folgen? 300

Es sind ja tatsächlich in den letzten Jahren eine 200 große Anzahl von Betrieben geschlossen worden und eine Reihe von traditionellen Faserproduzen- 100 ten hat sich sogar vollständig aus dieser Industrie 0 zurückgezogen. Die strategischen Marktanalysen 1990 1992 1994 1996 1998 2000 2002 2004 ließen einen zunehmenden Druck auf die Erträge Abb. 1. Produktionskapazitäten in Westeuropa (tpa). und ein langfristiges Schrumpfen des Verbrau- ches ihrer etablierten Produkte erwarten. Die Offenbar erfassen die Markanalysen der Schlüs- Konsequenz war in den meisten Fällen eine reine selproduzenten nur einen Teil des Bildes. Es „Melkstrategie“, die dann früher oder später zur stimmt jedenfalls, dass der Markt weder bereit Schließung während einer der nächsten Talpha- und wohl auch nicht fähig ist, weiterhin die von sen im Konjunkturzyklus führte. Vielfach ging den Faserproduzenten erwarteten hohen Margen man dabei auch von der Erwartung nach einer für Standardprodukte zu bezahlen; es stimmt besseren Auslastung der noch verbleibenden Ka- aber auch, dass man darauf auch anders als nur pazitäten aus, was jedoch in der Regel nicht mit Kapazitätsrücknahmen reagieren kann: die wirklich in Erfüllung ging, da der gesamte Markt Zukunft der Industrie liegt wohl ein weiteres Mal aus der pessimistischen Grundstimmung heraus darin, die Herausforderung anzunehmen und mit meist gleich mit verschwand. Auch Lenzing war dem Erledigen der „Hausaufgaben“ zu beginnen: von einem derartigen Fall betroffen, als wir uns nämlich die Kostenbasis zu reduzieren, die Um- der Entscheidung unseres Joint-Venture-Partners, weltprobleme zu lösen, die Qualität an die ge- die gemeinsame Polyesterstapelfaserfabrik in stiegenen Anforderungen der Weiterverarbeiter Lenzing zu schließen, nicht widersetzen konnten. anzupassen, neue Marktsegmente zu finden und Die Marktstruktur hat sich tatsächlich vollständig die Kunden mit neuen innovativen Spezialfasern geändert und die deprimierte Stimmung bei vie- zu unterstützen. Aber natürlich passt diese Art len Vertretern der Industrie ist durchaus begreif- von „Hausaufgaben“ nicht zu einer „Melkstrate- lich. Es stimmt, dass große Teile der textilen gie“. Die Lenzinger Großinvestitionen der letzten Produktion in Niedriglohn-Länder abgewandert Jahre können andererseits nur vor diesem Hin- ist und dass die Textilindustrie noch immer unter tergrund gesehen werden, und natürlich hat sehr dem Druck von Billigimporten stöhnt. Aber viel davon mit Forschung und Entwicklung zu stimmt es wirklich, dass diese Entwicklung, die tun. in den USA bereits zum fast schon vollständigen Verschwinden von Faserproduktion und Textil- 29

Lassen Sie mich deshalb einen weiteren kurzen (Qualität, Klima, ....), sie brauchen keine künstli- Abschnitt aus der Lenzinger Pressemitteilung che Bewässerung, keinen Kunstdünger und auch zitieren: Hier heißt es unter „Starke Nachfrage keine Pestizide. Lenzing hat die Umweltthematik nach Spezialfasern“: mit viel Einsatz aufgegriffen, so dass sie als vor- „Die positive Entwicklung des Fasergeschäftes bildlich gelöst gelten kann: gerade für integrierte der Lenzing Gruppe ist vor allem auf das breite Fabriken gilt, dass die Herstellung in nahezu Produktportfolio und die hohen Qualitätsstan- völlig geschlossenen Stoffkreisläufen und ener- dards zurückzuführen: „Die Spezialisierung und getisch nahezu autark erfolgen kann. Lenzing ist der Ausbau der Kapazitäten tragen jetzt Früchte, weltweit das führende Unternehmen in der „na- .... türlichen“ Welt dieser Technologien. Der Absatz von Lyocell konnte gegenüber dem Nicht umsonst hat die neue Lenzing-Lyocell un- Vorjahr signifikant gesteigert werden. Die Anla- ter allen europäischen Einreichungen den EU- ge in Heiligenkreuz ist voll ausgelastet. Mit die- Umweltpreis 2000 in der Kategorie „The Tech- ser Entwicklung wurden die Pläne übertroffen nology Award for Sustainable Development” und das Ergebnis konnte deutlich verbessert gewonnen (Abb.2)! werden. Der Absatz der Spezialfaser Lenzing Modal lag um 43% über dem Vergleichwert des Vorjahres. Sehr erfreulich verlief auch die Entwicklung bei Nonwovens-Fasern.“ Soweit die Pressemitteilung. Kontinuierliche Entwicklungsanstrengungen haben zu einer we- sentlichen Verbesserung des Produktportfolios geführt, so dass - ausgehend von etwa 30 % vor 10 Jahren - Lenzing in der Zwischenzeit mehr als 60 % seiner Produktion in Spezialitätenmärkten absetzt. Die Ausgangslage war natürlich hervorragend: Cellulose ist der wichtigste „organische Kon- struktions- und Funktionswerkstoff“ der Natur und weist dementsprechend eine umfassende Palette hervorragender und sehr spezifischer Ei- genschaften auf. Diese Eigenschaften können für verschiedenste Produkte zugänglich gemacht und auch gezielt modifiziert werden, sobald es einem gelingt, die Cellulose in Lösung zu bringen und sie dann in der gewünschten Form auf geeignete Abb. 2. EU-Umweltpreis 2000 für Lenzing Lyocell. Weise zu regenerieren. Die Verfahren entsprechen geradezu vorbildhaft Die Möglichkeit die Eigenschaften des Rohstoffs in der eigenen Zellstoffproduktion zu steuern, die der für unsere Zeit so wichtigen Vorgabe, mit nachwachsenden Werkstoffen nachhaltig zu breite technologische Basis mit dem Viscose-, Modal- und Lyocell-Verfahren ermöglicht ein wirtschaften. Der Verbrauch von Cellulosefasern steht im Einklang mit natürlichen Produktlebens- stetig wachsendes Angebot einer Vielzahl von Fasern für ganz spezielle Marktbedürfnisse. zyklen und geht einher mit einer Entlastung der Umwelt. Holz ist ein nachwachsender Rohstoff Für diese hohe Innovationsleistung ist naturge- mäß spezifische, hohe Kompetenz auf den Ge- und nahezu unbegrenzt verfügbar; die Produkte bieten der Holz-, Cellulose- und Fasertechnolo- sind CO -neutral (Treibhauseffekt / Kyoto) und 2 gien nötig. Rund 130 hochqualifizierte sind biologisch abbaubar (Deponieproblematik). Mitarbeiter bedienen sich dabei eines umfassen- Die Produkte entsprechen nach dem Ökotex den Instrumentariums von Technikumsanlagen Standard 100 der besten Klasse I. Die Ökobilanz und analytischen Methoden: ist im Vergleich zu allen Konkurrenzprodukten sehr günstig. Wälder nutzen Grenzertragsflächen 30

• für Holzaufschluss und -bleiche, Die Intensität des laufenden Innovationsprozes- • für Lösungsherstellung nach dem Visco- ses lässt sich anschaulich aus der Anzahl der seit se-, Lyocell- und Acetatverfahren, 1997 von Lenzing herausgebrachten neuen Spe- • für die Herstellung von Viscose-, Modal- zialitäten ablesen: Auf Basis des Viscose- und und Lyocellfasern und Modalverfahrens sind dies Viscostar, Viscofresh, • für Lyocell Folien und andere alternative, Modal Sun, Modal Fresh und eine Modal Color auf dem Lyocell-Prozess basierende Pro- Faser; auf Basis des neuen Lyocellverfahrens dukte. sind es ProModal, ProViscose, Lyocell, Lyocell Diese Kompetenz wird ergänzt durch kooperati- Tech und Lyocell NW (Abb.4). ve Projekte, durch langfristig etablierte koopera- tive Forschungseinrichtungen gemeinsam mit Universitäten und anderen Unternehmen und durch einen breit gestreuten Forschungs- diestleistungsverkauf, der es auch ermöglicht, das spezialisierte, teure Forschungsinstrumenta- rium besser auszulasten und überkritisch zu blei- ben. Als Träger der Innovationsbemühungen konnte sich die Lenzing auf diese Weise in den letzten Jahren ein einzigartiges Kompetenznetz- werk auf ihrem Gebiet aufbauen (Abb.3).

Abb. 4. Neue Lenzinger Spezialfasern seit 1997.

Alle Lenzinger Faserentwicklungen drehen sich naturgemäß immer auch um die einzigartigen, vor allem auch physiologisch hervorragenden Eigenschaften, die die Cellulose mitbringt. Nicht umsonst werden die Lenzinger Fasern durch Att- ribute wie “Makes the world a softer place“ (Lyocell) oder „The feel good fibre” (Modal) beworben. Es ist leicht einsichtig, dass gerade in Ländern mit hohen Durchschittstemperaturen und hoher Luftfeuchtigkeit das gute Klima- und Feuchtigkeitsmanagement von Cellulose unver- zichtbar für die tägliche Bekleidung ist. Doch gilt derartiges nicht nur für den Bekleidungssektor, Abb. 3. Kompetenznetzwerk Cellulose- und Fasertechno- sondern auch für die unterschiedlichsten nonwo- logie. vens-Anwendungen! Mit steigernder Weltbevöl- kerung und einem mit dem Wohlstand steigen- Obwohl die klassischen manmade Cellulosefa- den spezifischen Faserverbrauch wird auch der sern bereits über 100 Jahre alt sind, so wird doch Bedarf an Cellulosics weiter zunehmen (Abb.5). noch immer mit Erfolg intensiv an verbesserten Eines der wesentlichsten Entwicklungsvorhaben Eigenschaften und an neuen Fasertypen für spe- der Lenzing ist dementsprechend eine „Baum- zielle Anwendungen gearbeitet. Darüber hinaus wolle plus“, mit allen Vorteilen der bisherigen ist es Lenzing gerade in den letzten Jahren mit manmade-Cellulosics, aber ohne deren bisherige der neuen Lyocell-Technologie gelungen, eine Schwächen. Dies geschieht auf Basis der Lyo- neue Fasergeneration zu entwickeln und damit cell-Technologie, da Viscose aufgrund eines von einen großen Schritt auf dem Weg zu einem noch Baumwolle zu verschiedenen Eigenschaftsprofils breiteren und vielseitigeren Einsatz von manma- hierzu nicht in der Lage ist. Lyocell stellt bereits de cellulosics weiterzukommen. heute einen großen Fortschritt in Richtung 31 baumwollähnlicher Eigenschaften dar (Abb.6) denen bisher ausschließlich hochwertigste und findet schon Anwendungen in Bereichen, in Baumwolltypen zum Einsatz gelangten.

Abb. 5. Entwicklung des Weltfaserverbrauchs (Mio t) 1950 bis 2010.

Elastizitätsmoduli lässt zwar insgesamt höhere Werte bei Cellulose I erwarten, indiziert aber noch immer ein theoretisches Verbesserungspo- tential um eine ganze Größenordnung bei Cellu- lose II (Abb.7).

Abb. 6. Faserdaten ausgewählter Cellulosics.

Die Kraft-Dehnungskurven von Lyocell und Baumwolle haben im Bereich niedriger Dehnun- gen fast identen Verlauf. Das Arbeitsvermögen von Lyocell ist sogar um vieles höher, die Nass- eigenschaften sind die besten unter allen man- made-Cellulosics, und auch Sprödigkeit bzw. Schlingenfestigkeit sind hervorragend.

Fasern E [GPa] Praktisch Berechnet(*) Hanf (Cellulose I) 29 136 Baumwolle (Cellulose I) 6 – 11 136 HT-Rayon (Cellulose II) 13 89 Viskose (Cellulose II) 4 – 9 89 Abb. 7. Elastitzitätsmoduli ausgewählter Cellulosics (*) Cellobiose-Molekül als Grundeinheit [MM2HB mole- cular mechanics program].

Insgesamt ist das theoretische Potential der po- lymeren Werkstoffe mit Bezug auf mechanische Eigenschaften auch bei Cellulose noch bei wei- Abb. 8. Fibrillationsverhalten von Cellulosics. tem nicht genutzt: die Differenz zwischen ge- messenen und quantenmechanisch berechneten 32

Hauptthema der Entwicklungsanstrengungen bei Dies bewirkt im mit dem sehr anderen Lyocell bleibt derzeit jedoch die Suche nach Mikro-Aufbau der Cellulosematrix bei Lyocell Wegen für die Steuerung des relativ hohen nicht nur eine andere Optik und Haptik, sondern Fibrillationsniveaus (Abb. 8), das derzeit für un- auch deutliche Unterschiede mit Bezug auf den vernetze Lyocellfasern noch einen gewissen Strömungswiderstand, die thermische Isolation Aufwand für zusätzliche Veredelungsschritte und die Wasserdampfsorption. Lyocell kann er- erforderlich macht, wenn man sie für manche staunlich große Feuchtigkeitsmengen reversibel textile Applikationen einsetzen will. speichern (Abb.10). Im Rahmen einer Einstiegsmarketing-Strategie Aus derartigen Unterschieden wiederum lässt und bis zum Erreichen des genannten Zieles ei- sich vielleicht verstehen, warum Lyocell im Ver- ner allgemein und einfach einsetzbaren Massen- gleich zu anderen Fasern ein gänzlich anderes Textilfaser ist die Produktentwicklung bei Lyo- Mikroklima in den Hautkontaktzonen und damit cell durch eine möglichst zielgerichtete Nutzung wiederum signifikant unterschiedliche tragephy- spezifischer Eigenschaften für einzelne high-end siologische Eigenschaften hat. Nischen geprägt. Es handelt sich hierbei einer- Ein weiteres Gebiet, auf dem spezifische, inhä- seits um den Lenzinger Schwerpunkt Nonwovens rente Eigenschaften von Lyocell den Weg für Anwendungen aber auch um Heimtextilien mit überraschend neue Anwendungen öffnen, ist einem Einsatz bei Bett-, Frottier- und Dekotexti- deren vergleichsweise hohe Reinheit. Neben den lien. Bei ihnen spielt der natürliche Ursprung, die vielfach diskutierten Resten von Pestiziden ent- Reinheit, der Komfort und die Ästhetik neben hält Baumwolle ganz natürlich auch vergleichs- der grundlegenden textilen Performance eine weise sehr hohe Anteile von Schwermetallen besondere Rolle. Teilweise sind es höchst über- (Abb.11). Viscose enthält als Verunreinigungen raschende Aspekte, die interessante neue Produk- vor allem aus dem Herstellprozess stammendes te ermöglichen. So ähnelt z.B. die Faseroberflä- Natrium und Restschwefel. che von Lyocell, im Gegensatz zu den Viscosetypen eher der von Synthetics (Abb.9). Cotton Lyocell Fe 39,4 3bis5 Zn 20,2 1bis3 Cr <0,6 Ni <0,4 Pb <0,2 Cu <0,2 Cd <0,01 Abb. 11. Schwermetallgehalt von Baumwolle und Lyocell (mg/kg).

Lenzing Tencel Lenzing Lenzing Lyocell Viscose Viscose Abb. 9. Quer- und Längssicht von Viscose, Modal und normal- chlorfrei- Lyocell. gebleicht gebleicht 3 min 134 °C 0-1-2-5 10 min 126 °C 0-1-2-6 15 min 121 °C 0-2-2-6

4 min 138 °C -1 -2 -3 -7 15 min 138 °C -2 -3 -7 -11 30 min 138 °C -5 -4 -11 -15 Abb. 12. Vergilbung: Abfall des Tappi-Weißgrades nach Wärmebehandlung (Sterilisation).

Da reine Cellulose aber auch nahezu rückstands- frei pyrolisiert, kann diese Reinheit z.B. für die Abb. 10. Feuchtigkeitsaufnahme von Füllfasern. Herstellung keramischer Katalysatoren mit genau 33 steuerbarer Porenstruktur verwendet werden. Die und die Fähigkeit der Cellulose, Moleküle zu hohe Reinheit ist auch eine der Ursachen dafür, trennen, machen derartige Folien füreineReihe dass Lyocell bedeutend unempfindlicher gegen neuer und hochwertiger Membranapplikationen intensive Wärmebehandlung ist, dass sie z.B. bei wesentlich besser nutzbar, als dies mit Cellophan der Sterilisation deutlich weniger vergilbt als der Fall ist. Derartige „Lyophan-Folien“ können andere Cellulosics (Abb.12). z.B. auch als osmotische Membranen in Wasser- reinigungscontainern zum Einsatz gelangen Über die Anwendung in Fasern hinaus scheint (Abb.14, 15). sich aber mehr und mehr zu bestätigen, dass sich die teuer entwickelte NMMO Lösungs- und ÜBERSCHRIFT Rückgewinnungstechnologie auch für alternative Produkte nutzen lässt (Abb. 13). In Kooperation mit Firmen, die marktseitig andere Interessen haben, ist Lenzing deshalb intensiv mit der Ent- wicklung neuer Produkte auf Basis dieser Tech- nologie beschäftigt.

verkaufen, lizensieren Projekt: „Alternative NMMO- Lösungs Produkte: screening und Technolgie Vorversuche“ (etwa 0,3 25 MioEuro MioEuro)

Faserspinn- alternative Technologie Verformungs- 25 MioEuro Technologien Rückgewinnungs 25-30 Technologie MioEuro 25 MioEuro

einsetzten, Lenzing Kerngeschäft: kooperieren Stapelfasern Abb. 15. Osmotischer Wasserreinigungs-Container. Abb. 13: Alternative Produkte durch Lyocell-Technologie. Die offeneren Cellulosestrukturen ermöglichen einerseits einen wesentlich verbesserten Wasser- Cellulose in der Lösung: höheres Molekulargewicht niedriger Konzentration 20 transport durch die Membran hindurch, während Pressure Flux andererseits eine feine Innenbeschichtung der (l/m2/hr) Membran die Dialyse der vorgelegten Substan- 15 zen (z.B. Zucker) aus der Osmosezone heraus A. Smith, et al. (UCB Films/ Lenzing), Lenz. Ber. 80 (2001), 34 verhindert. Der osmotische Druck und die Hy-

10 Osmotic Films drationsrate bleiben hierdurch ausreichend lange aufrecht. Fällbad: zunehmende Temperatur und NMMO Koncentration Bei all diesen „neuen Anwendungen“ des Lyo-

Packaging Films 5 Viscose Filme cell-Verfahrens wird deutlich, dass die direkte NMMO Filme: “standard fibre conditions” Gase im Luftspalt Industrial Films Regeneration der Cellulose aus organischer Lö-

Querver- sung eine völlig neue Nutzung ihres hervorra- streckung (TD) 0 50 100TD Tensile Index 150 (MPa) genden Eigenschaftspotentials ermöglicht. Lyo- cell öffnet also nicht nur die Chance füreine Abb. 14. Permeabilität von Lyophanfolien. neue Generation cellulosischer Fasern - auch für ganz neue Einsatzgebiete - sondern auch die ei- So wird derzeit z.B. an der Herstellung neuer ner Renaissance der Cellulose in verschiedensten Schwammstrukturen aus Celluloselösungen in Werkstoffen, die einerseits, wegen der Notwen- NMMO gearbeitet. Weiters konnten Folien ent- digkeit zu derivatisieren, in den letzten Jahrzehn- wickelt werden, deren Eigenschaften durch die ten dem zunehmenden Substitutionsdruck voll- Wahl geeigneter Prozessparameter in weiten Be- synthetischer Polymerer weichen mussten und reichen beeinflussbar sind. Die guten mechani- die andererseits völlig neue Produkte ermögli- schen Eigenschaften, die erreichbaren Flussraten chen werden. 34

Zusammenfassend lässt sich feststellen, dass es Stabilität und Langfrist-Denken. So wie Produk- sehr wohl möglich ist, in Europa mit Fasern er- tionsanlagen nicht ohne langfristig wirksame folgreich zu sein, wenn man die Herausforderun- Instandhaltung und Ersatzinvestitionen funktio- gen annimmt und sich neu auf die traditionellen nieren können, so kommt es ohne konsistente Tugenden der typisch europäischen produzieren- und kontinuierliche Forschungsanstrengungen den Industrie besinnt. Die jüngsten Vorkomm- und gut ausgebildete und motivierter Mitarbeiter nisse in einer Reihe von „Mega-Dienstleistern“ auch zu keinen innovativen Produkten und neuen und sogenannt „neuen“ IndustrienindenVerei- Technologien. Auch hierfür bedarf es eines spe- nigten Staaten haben klar gemacht, dass kontinu- ziell sorgsamen Umgangs und gezielter Maß- ierliche Steigerungsraten und ununterbrochen nahmen im Sinne eines langfristigen Kompe- zweistellige Profitabilitäten entgegen dem zeit- tenzaufbaus, wobei sich die Zeichen mehren, weiligen Anschein doch nicht realistisch sind. dass man auch der Verfügbarkeit des Nachwuch- Wir haben gute Chancen, wenn wir uns auf Effi- ses wesentlich mehr Augenmerk widmen muss zienz, Flexibilität und Diversifikation konzent- als bisher. rieren. All das erfordert aber eine Kultur von 35

LYOCELLMISCHUNGEN - DER ZUSATZNUTZEN FÜR DIE TEXTILINDUSTRIE

Reinhard Kampl, Johann Leitner

Lenzing AG, A – 4860 Lenzing, Austria e-mail: [email protected] / [email protected]

Lyocell-Fasern unterscheiden sich von den Konstruktionen in der Fläche können die herkömmlichen, bisher am Markt bekannten positiven Eigenschaften dieser Faser- Zellulosefasern durch ihr umweltfreundliches generation - gepaart mit den Fasereigen- Herstellungsverfahren und ihre hervor- schaften des Mischungspartners, z.B. ragenden Fasereigenschaften, wie Festigkeit Modalfasern - zu hervorragenden Produkten im trockenen und nassen Zustand, und durch führen, die sowohl modisch als auch die ausgezeichnete Dimensionsstabilität der kommerziell äußerst interessant sind. Die daraus hergestellten Flächengebilde. Verwendung von Rotorgarnen ermöglicht Außerdem zeichnen sich Flächengebilde aus eine besonders wirtschaftliche Herstellung Lyocell aufgrund ihrer speziellen Fasereigen- von Endprodukten, die hohe Qualitäts- schaften in ihrer Ästhetik, wie Optik und anforderungen erfüllen, wie dies bisher noch Brillianz, zusätzlich durch einen kühlen, nicht möglich war. trockenen Griff aus. Für die im Vortrag vorgestellten Lyocell- Lyocell-Fasern unterscheiden sich wesentlich Artikel sind keine speziellen Veredelungs- von klassischen Zellulosefasern, vor allem schritte, wie sie bisher für diese Faser- durch ihre hohe Fibrillationsneigung. Die generation notwendig waren, erforderlich, Fibrillation ermöglicht einerseits die d.h., für die Ausrüstung dieser Artikel wurde Herstellung bzw. Produktion von ein normaler Maschinenpark, wie er für die verschiedenen modischen Griff/Optik- bekannten Zelluloseregeneratfasern ver- Effekten, andererseits können durch die wendet wird, eingesetzt. Die Kombination von Fibrillation sowohl in der Verarbeitung/ Produktivität, User-Economics, gepaart mit Veredelung als auch im Fertigprodukt einer hohen Fertigprodukt-Qualität zeigt Probleme auftreten. Durch geschickte interessante Vorteile für den Endverbraucher. Mischungskombinationen und ______

Lyocell-Mischungen - der Zusatznutzen für die Produktion von Spezialfasern gelegt. Neben die Textilindustrie den am Markt sehr erfolgreich etablierten Produkten, wie Modal, schwer-entflammbare Lyocell-Fasern unterscheiden sich von den Viscosefasern, Spezialfasern für Nonwovens und herkömmlichen - bisher am Markt eingeführten Spinnfarben, produzieren wir seit 1997 auch - Cellulosefasern durch ihr umweltfreundliches Lyocellfasern. Lyocellfasern stellen die neueste Herstellungsverfahren und ihre hervorragenden Generation von Cellulosefasern dar und Fasereigenschaften, wie z. B. der Festigkeit im unterscheiden sich wesentlich durch die trockenen und nassen Zustand, und durch die Fibrillierneigung. Die Fibrillation ermöglicht ausgezeichnete Dimensionsstabilität der daraus einerseits die Herstellung bzw. Produktion von hergestellten Flächengebilde. verschiedenen modischen Griffoptiken, Die Lenzing AG ist weltweit führend auf dem andererseits können dadurch - sowohl im Gebiet der Cellulosefasern. Das Portfolio Fertigprodukt wie auch in der Verarbeitung - umfasst nicht nur reguläre Viscosefasern, ein Probleme auftreten (z. B. ein höherer Anfall an 2. besonderer Schwerpunkt wird in Lenzing auf Qualität). 36

Durch geschickte Mischungskombinationen Markteinführung dieser Fasergeneration zu undKonstruktioneninderFlächekönnendie beschleunigen. positiven Eigenschaften von Lyocellfasern - Lyocellfasern wurden bisher hauptsächlich in gepaart mit den Eigenschaften der hochpreisiger Designerbekleidung eingesetzt. Die Mischungspartner, wie Baumwolle, Modal oder Verwendung von Lyocell bei der Herstellung von Viscose - zu hervorragenden Produkten führen, Textilien verlangt jedoch spezielle die sowohl modisch als auch kommerziell Verfahrensschritte, die kostenintensiv und äußerst interessant sind. arbeitsaufwendig sind, z. B. enzymatische Die textilen Eigenschaften von Lyocell sind mit Ausrüstung. Dieser Umstand hat bisher den jenen von hochwertigster, langstapeliger Einsatz von Lyocell limitiert. Baumwolle zu vergleichen, bzw. sind dieser, Unsere Marketingpolitik geht nun dahin, mit der wie später noch demonstriert, sogar überlegen. Entwicklung neuer Fasertypen und Textil- In der Nassfestigkeit eröffnen sich für konstruktionen breitere Anwendungsgebiete zu cellulosische Fasern bisher ungeahnte erschließen, die die vorhin aufgezeigten Möglichkeiten. Hindernisse beseitigen. Während Baumwolle mit einem weltweiten Bessere User-Economics sind für die Anwender Angebot von ca. 19.000.000 t – davon von großer Bedeutung und können mit Produkten langstapelige Baumwolle mit 600.000 t – in der aus Lyocell bzw. Lyocell- Textilindustrie gut eingeführt ist, steht die Mischungskombinationen in folgenden Markteinführung von Lyocell am Beginn. Einsatzbereichen gut umgesetzt werden.

Mio. Tonnen `000 Tonnen 60 400 50 350 40 Synthetische Fasern 300 Zellulosische Fasern 30 250 W olle 20 Andere BW 200 Synth. Fasern 10 150 Zell. Fasern 0 100 BW 1950 1960 1970 1980 1990 1998 2000 50 0 Arbe its- Techn. Be tt- Möbelbezug & HA KA DO B bekleidu ng Ge w e be 3 ) wäsche 1) Deko 1) Hemden 2) Blusen2) Abb. 1a. Weltfaserverbrauch. 2) 1) ohne Irland, Dänemark, Griechenland, Schweden 2) ohne Irland, Dänemark, Schweden 3) ohne Dänemark

´000 Tonnen Abb. 2. EU Fasereinsatz. 600

500

400 Der in diesen Einsatzgebieten hohe Anteil von 300 Baumwolle kann mit Lyocell bzw. Lyocell- 200 geplanter Ausbau 100 Mischungskombinationen zur Erreichung derzeitige Kapazität 0 besonderer Eigenschaften gut ergänzt werden. BW Langstapel Modal Lyocell Speziell in hochindustrialisierten Ländern, wo einerseits qualitativ hochwertige Produkte gefragt Abb. 1b. Weltproduktion bzw. –kapazität. sind und andererseits Lohn- bzw. Herstellerkosten eine große Rolle spielen, können Lyocellmischungen als innovative und Die derzeit installierte Kapazität von Lyocell wirtschaftliche Alternative zu Baumwolle gesehen liegt bei ca. 100.000 t. Schon daraus ist werden. ersichtlich, dass dieser Fasergeneration künftig In den folgenden Ausführungen möchte ich einige ein besonderer Stellenwert gegeben wird und Möglichkeiten darstellen, wie Lyocell in somit eine universelle Anwendung angestrebt Kombination mit Mischungspartnern sinnvoll im werden muss. Hinblick auf Produktqualität und Die Lenzing AG sowie auch unsere Wirtschaftlichkeit eingesetzt werden kann. Hier Mitbewerber sind von der Zukunft von spielt die hohe Faserfestigkeit von Lyocell eine Lyocellfasern überzeugt und setzen verstärkt dominante Rolle, die in den verschiedensten entwicklungstechnische Maßnahmen, um die Mischungen Produkte ermöglicht, die bisher nicht 37 am Markt waren. Bei geeigneter wirtschaftliche Herstellung von Endprodukten, die Materialkombination ist es auch möglich die hohe Qualitätsanforderungen erfüllen, wie dies besondere Eigenschaft des Fibrillierens von bisher noch nicht möglich war. In der Lyocell zu umgehen, ohne spezielle Rotortechnologie, wo die Garnfestigkeit aufgrund Ausrüstungsverfahren verwenden zu müssen. der Fasereinbindung grundsätzlich schlechter ist Die besonderen Produkteigenschaften der als die von Ringgarnen, kommt die Faserfestigkeit Lyocell-Faser wie von Lyocell speziell zum Tragen. • Hohe Festigkeit Untersuchungsreihen, die vor nicht allzu langer • Excellente Maßstabilität Zeit mit dem Textilinstitut Denkendorf • Besonderer Griff durchgeführt wurden, zeigten, dass bis zur • Besondere Optik Markteinführung von Lyocell keine cellulosische müssen ideal kombiniert und ausgenützt Faser in der Lage war, die notwendigen werden. Setzt man in geeigneten Garnfestigkeiten von ca. 16 cN/tex, die für die Konstruktionen Lyocell oder Ketttauglichkeit in der Weberei notwendig sind, Lyocellmischungen ideal ein, kann man zu erreichen. hervorragende, wirtschaftlich hochinteressante Mit Lyocell sind wir nunmehr in der Lage, Produkte herstellen. Garnfestigkeiten zu erzielen, die unter In naher Zukunft wird eine nicht-fibrillierende ausgezeichneten Verarbeitungseigenschaften an Lyocellfaser unser Faserangebot ergänzen, der Rotorspinnmaschine hergestellt werden womit völlig neue Produktperspektiven eröffnet können und die zudem an der Webmaschine werden. Die Entwicklung wird in Kürze hervorragende Laufeigenschaften garantieren. Ein abgeschlossen sein und in kommerzielle weiterer Vorteil dieser hochfesten Faser ist, dass Produktion übergeführt. wir heute schon sagen können, dass wahrscheinlich in naher Zukunft der Schlichteprozeß für Lyocell-Rotorketten mit nicht 60 [cN/tex] allzu dichter Belegung entfallen kann bzw. ein 50 Lyocell Polyester Kaltschlichten völlig ausreichend ist. 40 Modal Viscose BW Untersuchungen, die wir in diese Richtung 30 angestellt haben, stimmen uns äußerst 20 optimistisch. Selbstverständlich wird es hier 10 notwendig sein, spezielle Spinnmittel zur 0 0 2,5 5 7,5 10 12,5 14 15 17,5 20 30 [%] Anwendung zu bringen, da auch die Haarigkeit einen entscheidenden Einfluss hat, und nicht nur Abb. 3b. Kraft-Dehnungsverhalten. die Faserfestigkeit von Bedeutung ist. Wie Beiträgen der Fa. Schlafhorst entnehmbar, wurden Die neue, nicht fibrillierende Lyocell-Faser ist bereits Entwicklungen mit Lyocell und Lyocell- so konstruiert, dass man das Fibrillieren der Mischungen, die in diese Richtung gehen, Textilien vom absoluten Nicht-Fibrillieren bis durchgeführt, und diese sind sehr zu einem gewünschten Fibrillieren steuern vielversprechend ausgefallen. kann. Mit dieser Faser eröffnen sich völlig neue Für alle Lyocell-Mischartikel, die wir bisher Perspektiven, wobei die idealen End- entwickelt haben, sind keine speziellen einsatzbereiche, wo die Stärken dieser Faser Veredelungsschritte, wie sie bisher für diese voll zum Tragen kommen, erst herausgearbeitet Fasergeneration erforderlich waren, notwendig. werden müssen. D.h., für die Ausrüstung dieser Artikel wurde ein Ich möchte heute einige Beispiele normaler Maschinenpark, wie er für die heute am demonstrieren, wo Lyocellfasern in Intim- oder Markt befindlichen bekannten Cellulose- Systemmischung mit Viscose, Modal oder Regeneratfasern verwendet wird, eingesetzt. Baumwolle verarbeitet worden sind, wobei Textilien mit besonderen Eigenschaften hergestellt werden konnten. Es kommen Lyocellfasern mit normalen Fibrillier- Eigenschaften zum Einsatz. Die Verwendung von Rotorgarnen ermöglicht eine besonders 38

Modal / Lyocell-Mischungen Dehnung %

Im Rahmen interner Vergleiche wurden die 14 14 14,1 13,1 charakteristischen Eigenschaften von 100 % 11,2 11,3

Lyocell, 100 % Modal und einer Mischung Kette Modal/Lyocell untersucht. Das Mischungs- Schuß verhältnis wurde mit 70 % Modal und 30 %

Lyocell gewählt. 100 % CMD 1,3 Mischung 100 % CLY 1,3 Alle Gewebe wurden aus Ringgarn der Feinheit Modal/Lyocell Nm 50/1 in identer Konstruktion bei gleichen Verarbeitungsbedingungen in unserer Weberei hergestellt. Sämtliche Gewebe wurden gesengt, Abb. 5. Modal/Lyocell-Mischungen: Gewebevergleich – breit vorbehandelt und im Jet reaktiv gefärbt. Ringgarn Nm 50/1: Dehnung. Alle Varianten wurden hochveredelt, wobei praxisübliche Kunstharzmengen (50 g/l) Pilling gewählt wurden. Die Ergebnisse lassen sich wie Die Pillingprüfung nach Martindale der geprüften folgt interpretieren: Artikel zeigt ein interessantes Ergebnis. Über den gesamten Verlauf des Pillingtests zeigt das Gewebefestigkeit Gewebe aus 100 % Lyocell ein gleichmäßiges Auf Grund der hohen Garnfestigkeiten von Pillverhalten. Lyocellgarnen, liegt die Festigkeit des Gewebes Mit der Pillnote 4,5 (Bestwert 5,0) liegt das aus 100 % Lyocell mit 80 daN deutlich über Ergebnis der Pillingprüfung auf einem sehr hohen den Festigkeiten von Geweben aus Modal. Aus Niveau. Mit der Pillnote 4,5 zeigt die der Praxis wissen wir, dass Mischungen die Modal/Lyocell-Mischung ein gleich gutes Eigenschaften textiler Flächen optimieren. Ergebnis wie 100 % Lyocell und ist signifikant günstiger als das Gewebe aus 100 % Modal.

Festigkeit daN

Pilling Martindale Note 80 68 61 60 5 50 54 4,5 4 K ette 3,5 Schuß 3 125 Zyklen 2,5 500 Zyklen 2 2000 Zyklen 100 % CMD 1,3 Mischung 100 % CLY 1,3 1,5 Modal/Lyocell 1 100 % CMD 1,3 Mischung 100 % CLY 1,3 Abb. 4. Modal/Lyocell-Mischungen: Gewebevergleich – Modal/Lyocell Ringgarn Nm 50/1: Festigkeit. Abb. 6. Modal/Lyocell-Mischungen: Gewebevergleich – Die Modal/Lyocell-Mischung führt zu einer Ringgarn Nm 50/1: Pilling. Steigerung der Gewebefestigkeit um etwa 10 % im Vergleich zum Gewebe aus 100 % Modal. Dieses Ergebnis war auf Grund der erhöhten Dimensionsstabilität Es ist darauf hinzuweisen, dass die Maßänderung Garnfestigkeit der Mischung Modal/Lyocell von 100 % Viscose und 100 % Modal auch zu erwarten. grundsätzlich etwas höher liegt als Baumwolle bzw. Lyocell. Durch die Beimischung von Lyocell konnte die Dimensionsstabilität des Misch- Gewebedehnung gewebes gegenüber von 100 % Modal deutlich Die Modal/Lyocell-Mischung führt zu keiner verbessert werden. Änderung der Gewebedehnung im Vergleich zu Artikeln aus 100 % Modal, ist aber signifikant günstiger als Artikel aus 100 % Lyocell. 39

Maßänderung nach 25 Wäschen (%) Lyocell-Rotorgarn einem 100 % Baumwoll- Ringgarn - in der richtigen Konstruktion

-0,6 -0,6 -0,2 verwendet - signifikant überlegen ist.

-2,9 -2,5

Kette Schuß Pilling Martindale - Note nach 2000 Zyklen -6,2

100 % CMD 1,3 Mischung 100 % CLY 1,3 Modal/Lyocell 4,5 4 3,5 3 Abb. 7. Modal/Lyocell-Mischungen: Gewebevergleich – Ringgarn Nm 50/1: Massänderung.

100 % CLY 1,3 100 % CMD 1,3 50 % CMD 1,3 100 % BW Lyocell / Baumwoll - Mischungen Rotorgarn Ringgarn 50 % BW Ringgarn Ringgarn

In einem Gewebevergleich K 2/1 wurden verschiedene Kettgarne miteinander verglichen. Abb. 9. Lyocell-Baumwolle-Systemmischungen: Zum Einsatz kamen 100 % Lyocell Rotorgarn, Gewebevergleich – Köper 2/1, Nm 50/1: Pilling. 100 % Modal Ringgarn, 50/50 % Modal/Baumwolle Ringgarn und 100 % Baumwoll Ringgarn. Als Schuss wurde 50/50 Viscose / Lyocell Mischungen % Modal/Baumwoll Ringgarn verwendet. Wie dieser Gewebevergleich zeigt, können die Eine interessante Anwendung von Lyocell ist mit positiven Faser- und Garneigenschaften von Sicherheit in der Mischung Lyocell mit Viscose zu Lyocell trotz Verwendung von Rotorgarnen sehen. Durch die Beimischung von Lyocell zu hervorragend ins Fertiggewebe übertragen regulärer Viscosefaser werden sämtliche werden. textiltechnischen Parameter, die für die Verarbeitung bzw. für den Endverbraucher wichtig sind, signifikant verbessert. Als Beispiel Festigkeit K ette daN möchte ich mit einem Vergleich von Ring- und Rotorgarnen beginnen. Das Mischungsverhältnis 87 74 wurde auch hier mit 70 % Viscose und mit 30 % 71 69 Lyocell gewählt.

Garnwerte Bereits in der Spinnerei zeigt sich ein deutlicher

100 % CLY 1,3 100 % CMD 1,3 50 % CMD 1,3 100 % BW Einfluß der beigemischten Lyocellfaser. Rotorgarn Ringgarn 50 % BW Ringgarn Ringgarn Beginnend von der Spinnstabilität bis zu den Garneigenschaften, kann man den positiven Abb. 8. Lyocell-Baumwolle-Systemmischungen: Einfluß von Lyocell beobachten. Als Beispiel Gewebevergleich – Köper 2/1, Nm 50/1: Festigkeit. werden die Daten von 100 % Viscose, der Viscose/Lyocell-Mischung und 100 % Lyocell Neben den günstigen Festigkeiten hat Lyocell gegenübergestellt. Die Garnfestigkeiten auch einen sehr positiven Einfluss auf die demonstrieren hervorragend den positiven Einfluß Pillingresistenz. Die Pillingprüfung erbrachte von Lyocell. für diese Gewebekonstruktion eindeutig die besten Werte. Es ist klar erkennbar, dass ein 40

Garnfestigkeit cN/tex Garnfestigkeit cN/tex 28 - 29

19 - 20 16 - 17 17 - 18 13,5 - 14 11 - 11,5

100 % CV 1,3 Mischung 100 % CLY 1,3 100 % CV 1,3 Mischung 100 % CLY 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 10. Viscose/Lyocell Mischungen: Garnfestigkeit. a) Ringgarn Nm 50/1; b) Rotorgarn Nm 60/1.

Dehnung geringere Dehnung als Viscose aufweist, wobei Die Rotorgarndehnungen liegen bei den zwischen 100 % Lyocell und der Viscose/Lyocell- Mischungen naturgemäß etwas niedriger. Mischung fast kein Unterschied besteht. Deshalb, weil natürlich Lyocell eine signifikant

Dehnung (%) Dehnung (%)

12,5 - 13 11,5 - 12 10,5 - 11,5 10 - 10,5 8,5 - 9,5 8,5 - 9,5

100 % CV 1,3 Mischung 100 % CLY 1,3 100 % CV 1,3 Mischung 100 % CLY 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 11. Viscose/Lyocell Mischungen: Dehnung. a) Ringgarn Nm 50/1; b) Rotorgarn Nm 60/1.

Uster – Gleichmäßigkeit / U-CV Lyocell. Bei den Rotorgarnen liegen Viscose und Die Garngleichmäßigkeit von Ringgarnen aus die Viscose/Lyocell-Mischung graduell günstiger der Viscose/Lyocell-Mischung unterscheidet als 100 % Lyocell. sich nicht von 100 % Viscose bzw. 100 %

Uster CV Uster CV

14,5 - 15 14,5 - 15 15 - 15,5 11,5 - 12 11,5 - 12 11,5 - 12

100 % CV 1,3 Mischung 100 % CLY 1,3 100 % CV 1,3 Mischung 100 % CLY 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 12. Viscose/Lyocell Mischungen: Uster Gleichmäßigkeit. a) Ringgarn Nm 50/1; b) Rotorgarn Nm 60/1. 41

Imperfektionen der Viscose/Lyocell-Mischung kein signifikanter Für die Imperfektionen möchte ich Unterschied zu erkennen, hingegen ist 100 % stellvertretend die Dickstellen als Vergleich Lyocell deutlich ungünstiger. Die Dünnstellen und heranziehen. Hier zeigt sich, dass bei Noppen sind zwischen den verglichenen Ringgarnen die Dickstellen zugunsten der Provenienzen nicht verschieden. Viscose/Lyocell-Mischung ausfallen. Bei den Rotorgarnen ist zwischen 100 % Viscose und

Dickstellen Dickstellen 80

60 60

15 13 10

100 % CV 1,3 Mischung 100 % CLY 1,3 100 % CV 1,3 Mischung 100 % CLY 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 13. Viscose/Lyocell Mischungen: Dickstellen. a) Ringgarn Nm 50/1; b) Rotorgarn Nm 60/1.

Classimat und unterscheidet sich im Rotorgarn nicht von Der Classimatwert von der Viscose/Lyocell- 100 % Viscose. Mischung ist im Ringgarn signifikant günstiger

Classim at Classim at 130 120

80 90

30 30

100 % CV 1,3 Mischung 100 % CLY 1,3 100 % CV 1,3 Mischung 100 % CLY 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 14. Viscose/Lyocell Mischungen: Classimat. a) Ringgarn Nm 50/1; b) Rotorgarn Nm 60/1.

Kreppgarne Garnfestigkeiten Es ist überraschend, dass die Garnfestigkeiten bei Überzeugend ist der Vorteil von der der Viscose/Lyocell-Mischung der Festigkeit von Viscose/Lyocell-Mischung bei der Herstellung Garnen aus 100 % Modal deutlich überlegen sind, von Kreppgarnen zu dokumentieren. In einer obwohl die Einzelfaserfestigkeit dieser Mischung Versuchsreihe wurden Garne in Nm 34/1 mit α signifikant unter der Faserfestigkeit von Modal 230 mit zwei unterschiedlichen liegt. Ringläufergeschwindigkeiten hergestellt. Als Vergleich wurde Normalviscose 1,3 dtex sowie Modal 1,3 dtex zu Viscose/Lyocell-Mischung herangezogen. 42

11,9 11,5 10,3 10,4 8,8 9

100 % CV 1,3 Mischung 100 % CMD 1,3 100 % CV 1,3 Mischung 100 % CMD 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 15. Viscose/Lyocell Mischungen: Garnfestigkeit, Krepp Nm 34/1. a) 31 Rglfm/s; b) 38 Rglfm/s.

Dehnung niedrigeren Produktionsgeschwindigkeit beibehält, Auch hier überrascht, dass die Garndehnung wohingegen bei Viscose und Modal eine durch die Lyocell-Beimischung, speziell bei der Reduktion der Dehnung zu verzeichnen ist. höheren Liefergeschwindigkeit, das Niveau der

11,5 11,4 10,4 11,3 8,3 7,6

100 % CV 1,3 Mischung 100 % CMD 1,3 100 % CV 1,3 Mischung 100 % CMD 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 16. Viscose/Lyocell Mischungen: Dehnung, Krepp Nm 34/1. a) 31 Rglfm/s; b) 38 Rglfm/s.

Uster – Gleichmäßigkeit Die Viscose/Lyocell-Mischung liegt auf einem Die Garngleichmäßigkeit von Modal zeigt die leicht schlechteren Niveau, verändert sich aber günstigsten Werte und verändert sich auch mit auch bei höheren Ringspinngeschwindigkeiten hoher Ringspinngeschwindigkeit nicht. kaum, wohingegen die normale Viscose in der Garngleichmäßigkeit abfällt.

11,5 10,9 10,8 10,2 11 10,3

100 % CV 1,3 Mischung 100 % CMD 1,3 100 % CV 1,3 Mischung 100 % CMD 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 17. Viscose/Lyocell Mischungen: Uster Gleichmäßigkeit, Krepp Nm 34/1. a) 31 Rglfm/s; b) 38 Rglfm/s.

Imperfektionen Noppen aufweist. Auch hier zeigt sich, dass die Die Imperfektionswerte sind grundsätzlich als Viscose/Lyocell-Mischung im Vergleich zu gut zu bezeichnen. Ich möchte die Noppen normaler Viscose und Modal sehr positiv beurteilt stellvertretend für alle Imperfektionen werden kann. demonstrieren, da sich die Dünnstellen nicht signifikant unterscheiden und die Anzahl der Dickstellen einen vergleichbaren Wert wie die 43

18 16 14 14 12 10

100 % CV 1,3 Mischung 100 % CMD 1,3 100 % CV 1,3 Mischung 100 % CMD 1,3 Viscose/Lyocell Viscose/Lyocell

Abb. 18. Viscose/Lyocell Mischungen: Noppen, Krepp Nm 34/1. a) 31 Rglfm/s; b) 38 Rglfm/s.

Betrachtet man all diese Ergebnisse, so wird bleiben auf dem Niveau von Geweben aus 100 man feststellen, dass speziell die %Viscose. Viscose/Lyocell-Mischung im Bereich der Als Ergebnis dieser Entwicklungen zeigt sich, hochgedrehten Garne eine Bereicherung für die dass die Viscose/Lyocell-Mischung neben den Produktpalette darstellt, da auch neue besseren Gebrauchstüchtigkeiten einen deutlich Endanwendungen mit höheren schöneren Griff als 100 % Viscose aufweist. Drehungsbeiwerten als bisher üblich möglich Stellvertretend für die mechanischen sein werden, wodurch neue Optiken und Gebrauchstüchtigkeiten möchte ich die Griffvarianten realisiert werden können. Gewebefestigkeit und das Pillverhalten demonstrieren. Die Gewebefestigkeit spricht naturgemäß leicht Washable Rayon zugunsten von der Viscose/Lyocell-Mischung, das Pillverhalten liegt jedoch signifikant Im Rahmen eines Projektes für die USA günstiger als bei 100 % Viscose. (Washable Rayon) haben wir eine klassische Besonders hervorheben möchte ich jedoch Viscose-Druckware, wie sie heute im DOB- neben den mechanischen Gebrauchs- Bereich eingesetzt wird, zur Viscose/Lyocell- tüchtigkeiten die Eigenschaften, die im nassen Mischung verglichen. Die Konstruktion wurde Zustand von besonderer Bedeutung sind, wie in Leinwandbindung bei einem Flächengewicht den Längenverlust, der in der Ausrüstung von 130 g/m² gewebt. zwischen der Rohware und der Fertigware auftritt, sowie die Maßänderung der fertig ausgerüsteten Ware nach 25 Wäschen. Nicht unerwähnt soll bleiben, dass durch die Bindung: Leinwand höhere Festigkeit der Fasermischung eine Flächengewicht: 130 g/m² deutlich höhere Prozesssicherheit gegeben ist und der Anteil der Minderqualität erheblich Kettdichte 294 Fd/cm reduziert werden kann. Schußdichte 243 Fd/cm Die Prozesssicherheit ist durch die höhere Zugfestigkeit, eine deutlich höhere Kettgarn Nm 50 OE Einreißfestigkeit, das bessere Schußgarn Nm 50 Ring Schrumpfverhalten und den geringeren Längseinsprung gegeben. Abb. 19. Viscose-Lyocell-Mischungen: Washable Rayon Wie man sieht, zeigen die vorliegenden Daten Gewebekonstruktion. signifikante Vorteile für die Viscose/Lyocell- Mischung. Durch diesen Vergleich soll gezeigt werden, welche Vorteile durch eine Beimischung von 35 % Lyocell zu Lenzing Viscose ermöglicht werden. Der Ausrüstungsgang der Qualitäten wurde dem von 100 % Lenzing Viscose untergeordnet, d.h. die Kosten der Ausrüstung 44

Festigkeit daN Pilling Martindale Note

5 35 34 31 29 4,5 4 3,5 125 Zyklen Kette 3 2,5 500 Zyklen Schuß 2 2000 Zyklen 1,5 1 100 % CV 1,3 Mischung 100 % CV 1,3 Mischung Viscose/Lyocell Viscose/Lyocell

Maßverlust: Rohware - ausgerüstet (%) Maßänderung nach 25 Wäschen (%)

-2,4 -2,6 Kette -4,7 -4,3 Kette -6,2 Schuß -8,9 100 % CV 1,3 Mischung Viscose/Lyocell 100 % CV 1,3 Mischung Viscose/Lyocell

Abb. 20. Viscose-Lyocell-Mischungen: Washable Rayon Gewebekonstruktion.

Kundennutzen Zusammenfassung

Mischungen mit Lyocell sind - wie bereits Zusammenfassend möchte ich die wichtigsten mehrmals angeführt - einfach zu verarbeiten. Punkte noch einmal festhalten: Ein Maschinenpark, der für die Herstellung • Lyocellfasern zeichnen sich durch eine normaler cellulosischer Regeneratfasern Faserfestigkeit aus, die bisher für verwendet wird, erfüllt auch für die Zellulosefasern unerreichbar waren. Verarbeitung von Fasermischungen die • Die textilen Eigenschaften von Lyocell sind gestellten Anforderungen. mit jenen von hochwertigster, langstapeliger Die guten Faserdaten von Lyocell, eine Baumwolle zu vergleichen bzw. sind dieser optimale Fasermischung und entsprechend sogar überlegen. abgestimmte Konstruktionen bieten eine Reihe • Die derzeit installierte Kapazität von Lyocell vonVorteileninallenVerarbeitungsstufen. liegt bei ca. 100.000 t. Daraus ist ersichtlich, Von der Spinnerei, wo aufgrund der hohen dass diese Fasergeneration in der Festigkeit z. B. auch mit höherer Lieferleistung Textilindustrie in Zukunft eine universelle gefahren werden kann, bis hin zur Weberei, wo Anwendung finden wird, wobei die Lyocell-Rotorgarne oder deren Mischungen derzeitigen Hindernisse in den textilen mitunter sogar ohne Schlichte verarbeitet Verarbeitungsstufen ausgeräumt sein werden. werden können, ergeben sich quantifizierbare • Lyocell ist ein ausgezeichneter Vorteile für die gesamte textile Kette. Mischungspartner für nahezu alle am Markt Zum Thema „schlichtefreie Rotorgarne“ wird angebotenen Fasertypen. Bei entsprechendem im Anschluss Herr Rosery von der Firma Einsatz und gut gewählten Konstruktionen Schlafhorst ausführlich berichten. kann selbst bei einer fibrillierenden Ich möchte aber darauf hinweisen, dass neben Lyocellfaser auf zusätzliche aufwendige dem Entfallen der Schlichtekosten auch ein Färbe- und Ausrüstungsschritte, wie sie für Vorteil für die Umwelt gegeben ist, da kein Lyocell sonst notwendig sind, verzichtet CSB bzw. BSB durch Schlichteabbau anfällt. werden. Somit darf nicht nur das Argument der Kosten, • Kundennutzen für die Anwender stehen im sondern auch das Argument der Vordergrund und werden entsprechend Umweltfreundlichkeit getrost in den Mund umgesetzt und vermarktet werden. genommen werden. 45

• Lyocell ist aufgrund der ausgezeichneten Danksagung Trocken- und Naßfestigkeitseigenschaften bestens geeignet für die neuen Ich möchte mich bei den Firmen Borckenstein, Hochleistungstechnologien in der textilen Linz Textil, Wisselink und KBC sowie bei allen Kette. Hochleistungsgarnherstellung (OE, Kollegen meiner Abteilung, die bei der Erstellung Air Jet) und Hochleistungswebverfahren, dieses Vortrages mitgewirkt haben, für ihre wo sogar auf den Schlichteprozeß da und Unterstützung bedanken. dort verzichtet werden kann, werden für diese Fasergeneration keine Probleme darstellen. • Eine nicht fibrillierende Lyocellfaser wird in Zukunft unser Faserangebot ergänzen, womit völlig neue Perspektiven von gewünschter Fibrillierung bis hin zu Nicht- Fibrillierung von Textilien eröffnet werden. • hohe Festigkeit • exzellente Maßstabilität • besonderer Griff • besondere Optik. 46

IMPROVEMENTS IN PROCESSING OF TENCEL FIBRES AND FABRICS

Patrick A. White

Tencel – Acordis Fibres Ltd., Director R & D, P.O. Box 5, Spondon, Derby, DE217BP, UK Fax: +44 1332 681860

The TENCEL® manufacturing process has Recent advances in fibre crimping are been in commercial operation for 10 years described that have given significant now and has proved to be very successful improvements to the performance of the fibre technically, economically and environmen- during carding and yarn spinning. tally. TENCEL® garments in the market have Early advances in the dyeing and finishing of proved to have an excellent balance of TENCEL® were based on the use of enzymes. comfort, soft touch and performance. The New, more economical routes have now been range of garment types has expanded developed that can yield TENCEL® fabrics enormously in this period as the processing with the same comfort and performance technologies have been developed. attributes. These are outlined in this paper. ______

Introduction technology has had to be developed. I will explain the progress we have made. In 1992 a new cellulosic fibre was launched TENCEL® is comfortable to wear but, for this to commercially under the brand name be of most benefit, we need to deliver this to the “TENCEL®”. It was the first major new fibre for market at affordable prices. I will demonstrate 30 years and was generically classified as the degree to which we are now able to achieve Lyocell. It is 100 % natural in origin as it is this. made from wood pulp and is of high purity and fully biodegradable. It has superior textile performance and out-performs cotton and The new tow wash/crimping process viscose in many applications. TENCEL® garments are comfortable to wear because they The TENCEL® process route has been well are breathable and water absorbent. publicised and I will not dwell on it here. In As with most major new fibres, there have been outline, wood pulp is dissolved in NMMO many new challenges that need to be met before solvent, spun into an aqueous bath, then washed, the fibre can become widely used. In this paper I dried and cut. The solvent is recycled to a very will highlight the main issues that have arisen high level of efficiency. Much of the process and summarise the progress that has been made required new, high technology equipment and to successfully overcome them. procedures and these are now covered by a large TENCEL® is made by a new process route, and number of patents that have been granted we have needed to learn how to fully exploit its worldwide. inherent benefits. One key aspect that I will be This paper will cover one new feature of the discussing in this paper is the new fibre crimp TENCEL® production route that has not been route. discussed frequently - the use of a tow route to The fibre can produce fabrics that have excellent wash and dry the fibre. textile performance, but new dyeing/finishing 47

A NMMO solvent allows an Managed Forests elegant new process route

Pulp

Dissolve

Spin Purify

Wash Solvent

Dry Apparel

Staple Fibre Crimp/Cut

Figure 1. Tencel production route.

Traditional viscose staple fibres are normally some technical challenges because TENCEL® cut soon after spinning and then washed and is not an easy fibre to crimp. Dry cellulose is dried as a bed. This can lead to problems in not thermoplastic so we need to use steam to achieving product uniformity, avoiding fibre plasticise it. entanglements and difficulties in product changes. Fibre type Maximum carding speed For TENCEL® we chose to wash and dry the [m/min] fibre as an uncut tow to achieve uniformity and TENCEL HS260 250+ facilitate good quality control. The tow is then POLYESTER 200-250 mechanically crimped using a stuffer box LYOCELL 150-200 crimper to allow easy processing to yarns and VISCOSE ~150 non woven webs. This was a pioneering Table 1. Comparative Carding Speeds. technology for cellulose fibres. The crimped tow is then cut and baled on line. After many years manufacturing experience we The expected benefits of this tow route have have learned how to fine tune the control of the now been well demonstrated in practice. As crimping process. Recent technical advances well as achieving a uniform and consistent with crimper design and finish selection have product, the fibres are easily opened with a lead to major technical advances and, by the minimum of entanglements. They give either end of 2001, we were test marketing our first uniform card webs with a minimum of neps or new high crimp fibre – TENCEL® HS260. are readily processed by air laying equipment The benefits in terms of maximum card speed for non woven webs. Yarn quality is very good were remarkable – it processed smoothly at a in all aspects. very high carding speed on the Thibeau card on which the trials were carried out (Table 1). The Improvements in fibre processing webs formed in the trials were 30 gsm. characteristics In addition there were other significant benefits such as low fly generation, good web stability As expected, further improvements to this route and low nep levels. The form of the fibre is have been requested, the most important being very similar to that of polyester staple so to increase the fibre cohesion. This is blending with that fibre is very efficient. particularly important for high speed carding. The TENCEL® HS260 has been launched We quickly demonstrated that increased crimp commercially and customer reaction has been levels would be beneficial but this posed us very positive. 48

The high crimp fibre is also being developed fibre. The processing performance was good in for yarn spinning and results are again very all aspects and yarn regularity improved encouraging. Yarn processing and quality significantly. improvements are seen in most of the normally Further commercial scale trials are being monitored characteristics. In Table 2 are the carried out and we expect to make the fibre results from the first trial in a commercial mill. commercially available soon. The yarn was OE spun to 20Nm using 1.4dtex

TENCEL® TENCEL® High crimp YARN TENSILES TENACITY (cN/tex) 20 20 EXTENSION (%) 7.8 8.4 CV% (TENACITY) 7.9 5.8

REGULARITY %CV (UT3) 11.1 10.2

IMPERFECTIONS THICK PLACES +50% 2 1 (per 1000m) THIN PLACES –40% 21 12 THIN PLACES –50% 1 0 NEPS +200% 3 0 Table 2. Yarn quality data – commercial mill.

Advances in dyeing and finishing technology Development challenges for TENCEL® fabrics Early peach touch products required expensive In this section of the paper, I will discuss the process routes that, in many cases, required technologies that have played the most important specialist equipment. This particularly applied to part in the market development of TENCEL® - piece dyed fabrics. dyeing/finishing of fabrics and garments. The development of an understanding of the process fundamentals has enabled us to The TENCEL® touch is born significantly expand the process routes and reduce the costs. The key to this has been TENCEL® pioneered the soft, peach touch learning to manipulate the fibrillation of the fibre aesthetic in denim in Japan in 1992/94. Not only during the dyeing/finishing process. was the peach touch very popular, but the As is now well known, fibrillation occurs during garments that were on the market were the wet abrasion of the fibre and is the property fashionable in appearance and very comfortable that gives the characteristic peach surface to the to wear. They also proved to be durable in use. fibres. However, incorrect control of the This success with denim was replicated fibrillation can give unwanted effects to the worldwide in the following years. fabric appearance or handle. The big challenge that followed from this was to The use of enzymes was the key to early success. expand the processing range beyond denim. Enzymes were used to clean the fabric surface There was a very strong customer demand for the andalsotosoftenthefabric. TENCEL® touch to become available in a much Following these early discoveries, we expanded wider range of apparel – and at affordable prices. the range of processing machines that could be The market growth of TENCEL® has been very used to make commercial quality products – all significantly effected by the rate of technical based on the use of enzymes. Garment washing progress in developing economic processes to and dyeing was the next stage in the make soft touch fabrics. development since they were closest to the equipment used in denim processing. This was extended to piece dyeing by the use of the special Nidom machines in Japan and then to air 49 jet dyeing machines worldwide. Tumblers were times are required (~14 hours on a jet) and this also introduced for piece dyed products can restrict the total capacity of some dye worldwide. houses. The careful process control requirements also restrict the number of dye houses that can Manipulation of fibrillation successfully process the fabrics. We therefore need more economical alternatives So let us consider the basic principles to achieve routes that will give the same attractive a ‘peach’ aesthetic by the enzyme route. aesthetics, comfort and performance. Firstly you must remove the surface fibres/hairs One successful approach to this that we have on the fabric since it is these that will give developed is to use alternate chemicals instead of unsightly pills when the fibres are fibrillated. enzymes. I will outline our progress in this Next you fibrillate the fabric surface to give the below. peach touch. Then you tumble the fabric to The first of these alternative routes is to provide complete the clean up and give bulk and fullness chemical energy by a combination of oxidative to the fabric. degradation and causticisation. The oxidative The following is a typical process route using degradation is brought about by hydrogen enzymes. peroxide treatment during desizing and this is • In the pre fibrillation stage, the surface fibres followed by a causticisation treatment that are fibrillated by wet abrasion in either completes the process. The pre-treated fabrics garment or jet processing equipment. can then be dyed in an air jet, garment machine • Enzymes are then used in similar machines to or in pad dyeing. These pre-treatments weaken remove the surface fibres and fibrils. the surface fibres/hairs on the fabric so that they • The fabric is then subjected to wet abrasion – are readily removed by the mechanical action in possibly during the dyeing process – during the dyeing and tumbling stages. which the surface fibrillation is generated. A variation of this route is to apply the caustic Because the long surface hairs were removed and peroxide in a single stage then to pad batch in the earlier steps, the fibrils formed by this (PB) the fabric to allow the degradation process step are held close to the fabric surface so to occur. The pre-treated fabric can then be that pilling is avoided. dyed/tumbled etc as above. • A tumbling stage is then used to develop A third route we have developed is called ‘Resin further bulk and softness in the fabric. Beat’. This process exploits the brittleness of surface hairs/fibrils after resination of fabric. Different softener types can be used to refine the Fabric is allowed to fibrillate during a normal aesthetic and easy care resins are sometimes used dyeing and finishing process and then is given an to optimise appearance retention. after treatment with an easy care resin. The There are of course many variations on the theme fabric is then tumbled and the mechanical action of this route – each developed to suit market causes the surface pills to fall off the surface of needs and customers’ dye house facilities and the fabric. expertise. A whole new industry has been The resin beat process yields a slightly different developed over the last 10 years based on the ‘peach touch’ aesthetic to the other routes but it above principles and a very wide range of is still very attractive and fabric performance is attractive garments have been successfully very good. The fabrics retain their appearance delivered to the market. well after wash and wear cycles. The cost benefits of these new routes can be The next generation of finishing process appreciated by comparing the typical relative routes processing times of the different routes in the following table. We have taken the process time In order to enable TENCEL® to reach its true to make a soft touch cotton fabric as the base line market potential, further improvements in of 100. dyeing/finishing were called for. Enzymes are expensive products and need careful process control during use. Furthermore long process 50

Conclusions Process route Relative process time ® Cotton - jet dye 100 The new technologies in TENCEL fibre Tencel on Nidom 240 manufacture and the new performance characteristics of the fibre have opened up a Enzyme by air jet 210 large range of new product opportunities. Oxidative degradation 120 The TENCEL® tow process route offers a new Oxidative degradation range of product forms for cellulose fibres. (PB) 115 Modifications to the fibre crimp level and finish Resin beat 105 type will enable us to readily customise the fibre Table 3. Reductions in dyeing/finishing process time. for a wide variety of applications. The high strength of the TENCEL® fibre These new technologies are now gaining combined with its fibrillar nature allows a new acceptance in the market and we are increasingly family of dyeing/finishing techniques to be used confident that they will have a major impact on ® to broaden the range of comfortable fabrics that the commercial success of TENCEL in the perform well in use. The latest advances in coming years. dyeing/finishing technologies should help to unlock the large market potential for the fibre. 51

LENZING LYOCELL® FILL – DIE NEUE FÜLLFASER FÜRS BETT

D. Eichinger, W. Feilmair, J. Männer, P. Krüger Lenzing AG, A – 4860 Lenzing, Austria e-mail: [email protected]

In den letzten Jahren haben Füllfasern einen Wärmeisolation besitzt und durch einen enormen Stellenwert im Bettenbereich exzellenten Feuchtigkeitstransport besticht. erhalten. Aufgrund moderner Heizsysteme Es werden typische Füllmaterialien wie nimmt die Bedeutung der Wärmeisolation ab, Daune, Wolle und vor allem Polyester der wohingegen die Eigenschaften des neuen Faser Lenzing Lyocell® FILL Feuchtigkeitstransportes bzw. des Feuchtig- gegenübergestellt. Dabei wird der potentielle keitsmanagements an Wichtigkeit gewinnen. Einsatz von Lyocell in 100% und Mischungen Überraschenderweise wurde gefunden, dass bei kardierten Vliesen in Steppdecken, sich die Cellulosefaser Lenzing Lyocell als verfestigten Vliesen bei Matratzen und Füllmaterial dazu sehr gut eignet, da es eine Faserbällchen für Kissen vorgestellt. ausreichende Bauschkraft und damit ______

Einleitung Technologie ermöglicht die Herstellung reinster Fasern aus natürlichem, erneuerbarem Rohstoff Die Entwicklung von Füllfasern der neuesten und äußerster Reinheit, wie auch die Erfüllung Generation ist eine enorme Herausforderung, des Ökotex Standards 100 Klasse I beweist. zumal an diese vielfältigste Ansprüche gestellt werden. Neben der Isolationswirkung, sollte der Anforderungsprofil einer Füllfaser Artikel eine gewisse Bauschigkeit, kombiniert mit Weichheit, aufweisen. Zudem soll das Das Anforderungsprofil einer Füllfaser kann aus Füllmaterial ausreichende mechanische Stabilität den gewünschten Eigenschaften der Steppware zeigen. Obwohl Steppbetten eigentlich (noch) abgeleitet werden. So muss diese eine nicht zu Hygieneartikeln zählen, fordert der entsprechende Bauschigkeit, gute Konsument mit Recht ein sauberes Produkt. Dies Gebrauchswerte und optimale Komfortparameter bedeutet den Einsatz reinster Materialien. aufweisen. Im folgenden werden diese Zusätzlich sollte der fertige Artikel nach Kategorien und der diesbezügliche Stellenwert Möglichkeit auch noch waschbar konzipiert sein. von Lenzing Lyocell® FILL diskutiert. Dem Komfortfaktor ist im „feel well“-Zeitalter ein immer bedeutenderer Stellenwert Bauschigkeit einzuräumen. Das bedeutet, dass neben ausreichenden Isolationswerten auch das Die Bauschigkeit des Füllkörpers subsummiert Feuchtigkeitsmanagement optimal erfüllt sein im wesentlichen sein Volumen, die muss. Bauscherholung bei mechanischer Deformation Im letzten Jahr wurde die neue Faserinnovation und die resultierende Weichheit des Lenzing Lyocell® FILL – in silikoniserter Form Endproduktes. Übersetzt auf Faserebene ergeben mit 60 mm Stapellänge – vorgestellt. Diese Faser sich die Forderungen nach einer möglichst erfüllt obiges Anforderungsprofil und findet dreidimensionalen Raumausnutzung der Faser mittlerweile im Markt schon sehr guten Anklang. (idealerweise 3D-Kräuselung), einer Außerdem hat die europäische Umwelt- ausreichenden Elastizität der Faser sowie eines Kommission im Dezember 2000 dieser neuen optimal eingestellten Haft-Gleitverhaltens Lenzinger Fasertechnologie den begehrten zwischen den Füllfasern. Umweltpreis verliehen. Diese äußerst saubere 52

Kräuselung – die räumliche Ausdehnung der Materialeigenschaft über den Elastizitätsmodul Füllfaser beschrieben werden. Es wurden die Elastizitätsmoduli der wichtigsten Die Bauschigkeit des Füllkörpers wird durch Fasertypen ermittelt. Untersucht wurden dessen Herstellverfahren, die verwendeten Lenzing Lyocell® FILL 6,7 dtex, Viskose 8,9 Grammaturen, aber auch durch die eingesetzte dtex, Baumwolle, Wolle, PES Hohlfaser 7 dtex. Faser bestimmt. Auf Faserebene bedeutet dies, Im Quervergleich zeigt Lenzing Lyocell® FILL dass für die Erzielung einer guten Bauschigkeit sowohl im trockenen als auch nassen Zustand die bereits die einzelne Faser möglichst höchsten Moduli der betrachteten Fasern und dreidimensional den Raum ausfüllt und damit liegt somit auch höher als die für diesen Bereich dem Füllkörper an sich Volumen gibt (Abb. 1). bisher schwerpunktmäßig eingesetzte Wolle und Dieser Anforderung wird Lenzing Lyocell® Polyester (Abb. 2). FILL aufgrund des patentierten Herstellungsverfahrens (Patentnummer: AT Haft-Gleitverhalten 402.741; EP 0797696; US 6.117.378) gerecht. Das Verhalten bei Deformation und Wiederentlastung wird neben der Kräuselung und Steifheit der Faser auch durch das Haft- Gleitverhalten zwischen den Füllfasern bestimmt. Bei mechanischer Deformation werden die Füllfasern zum Teil ineinander verschoben. Die über die Steifheit der Faser gespeicherte Rückstellenergie kann sich nur dann wieder freisetzen, wenn das Haft-Gleitverhalten der Einzelfasern dies zulässt. Auch die subjektiven Eigenschaften wie Weichheit des Füllmaterials und Griff werden davon mitbestimmt. Durch eine entsprechende Avivierung, sprich Abb. 1. Kräuselung Lenzing Lyocell® FILL 6,7/60 mm. Silikonisierung, der Faser kann das Haft- Gleitverhalten optimal eingestellt werden. Die Prüfung der Wiedererholung eines Füllmaterials 8 und damit der Bauschelastizität zeigt die Modul kond bei 1% Wirkung dieser Avivierung, wie Abbildung 3 6 BISFA Modul nass bei 5% zeigt. Für die Prüfung wurde 3 g Vlies in einem Messzylinder mit einem Gewicht von 1 kg 15 4 Minuten lang belastet und anschließend wieder entlastet. 2

0 12 CLY FILL CV BW Wolle PES Belastung 10 1kg Abb. 2. Vergleich der Moduli. 8 6 cm

4 Entlastung / Wiedererhol Elastizität 2 ung 0 Für den Erhalt der Bauschigkeit Lenzing Lyocell Lenzing Standard LYOCELL FILL (Bauschelastizität) muss die Füllfaser ihre silikonisiert räumliche Ausdehnung auch bei Deformation und Wiederentlastung des Füllkörpers Abb. 3. Wiedererholung von Vliesen bei mechanischer aufrechterhalten. Als gute Näherung kann diese Belastung. 53

Zusammengefasst zeigt Lenzing Lyocell® FILL von Steppdecken zeigt, dass eine Füllung mit hinsichtlich ihrer mechanischen Eigenschaften 100% Lenzing Lyocell® FILL mit Naturfasern sehr gute Grundvoraussetzungen für den Einsatz (Wolle und Seide) vergleichbare Volumina als Füllfaser. Ein praktischer Vergleich anhand ergibt.

100% Seide 100% Wolle 100% Lenzing Lyocell® FILL 0,48kg/m2 0,57kg/m2 0,52kg/m2

Abb. 4. Vergleich der Deckenvolumina von Füllungen aus Seide, Wolle, Lyocell.

Gebrauchswerte Polyester vergleichbar mit der Steppdecke aus 100% Polyester ist. Durch Mischung von Zigarettenbrenntest Lenzing Lyocell® FILL mit Polyester kann ein Um den immer strenger werdenden Vorschriften mit 100% Polyester vergleichbares Bausch- und genüge zu tun, hat die Firma Hefel an den Waschergebnis erzielt werden. Steppdecken mit 100% Lenzing Lyocell® FILL Für den Objektbereich wurde gemeinsam mit der und eingehüllt in ein Inlett aus 100% Lenzing Firma Hefel und der Firma Wozabal ein Lyocell® MICRO an den Steppdecken Opal (1 Vergleichstest von Steppdecken im industriellen Wärmepunkt), Jade (4 Wärmepunkte) und am Maßstab durchgeführt. Zielrichtung war die Kissen Onyx den Zigarettenbrenntest am ITF Entwicklung einer atmungsaktiven Steppdecke durchführen lassen. Diese Produkte haben den für Krankenhäuser und Pflegeheime. Dabei Zigarettenbrenntest gemäß „Decret no 2000-164 wurden eine derzeit im Einsatz befindliche du 23 fevrier 2000 suivant les normes NF EN Steppdecke aus 100% PES mit wiederum einer 12952“ bestanden. 50% Lenzing Lyocell® FILL / 50% Polyester – Mischung verglichen und insgesamt 50 mal Waschbarkeit gewaschen. Die optische Beurteilung zeigt, dass Durch die immer häufiger auftretende die Lyocell-Mischung nach 50 Wäschen die Hausstauballergie und selbstverständlich auch gleiche Vliesbeständigkeit aufweist, wie 100% aus Hygienegründen wird vermehrt im Konsum- Polyester. Auch das Volumen der beiden aber vor allem im Objektbereich die Steppdecken (Abbildung 5) ist vergleichbar. Waschbarkeit von Steppdecken gefordert. Die Haushaltswäsche gestaltet sich mitunter Volumen von Steppdecken (Fa Hefel) nach 50 schwierig, da oftmals das Füllvolumen der Industriewäschen (Fa.Wozabal) Waschmaschine nicht ausreicht, um beispielsweise Decken mit mehr als 3 75% Wärmepunkten waschen zu können. Vergleicht man nun Steppdecken mit 100% Lenzing 50% ® ® Lyocell FILL, 50% Lenzing Lyocell FILL / 25% 50% Polyester Hohlfaser 7dtex und 100% 0% Polyester Hohlfaser 7dtex mit jeweils 3 50% CLY / 50% PES PES Wärmepunkten, so zeigt die Steppdecke aus ® 100% Lenzing Lyocell FILL nur eine sehr Abb. 5. Deckenvolumen nach Industriewäsche. eingeschränkte Wasch- und Vliesstabilität (verliert nach 5 Wäschen ca. 50% an Volumen), während die Vliesstabilität der Mischung mit 54

100% PES hohl 7dtex 50% Lenzing Lyocell® FILL 0,65kg/m2 50%PES 0,78kg/m2

Abb. 6. Vergleich der Deckenvolumina von Füllungen aus 100% PES und Mischung PES 50% / Lenzing Lyocell® FILL 50%

® Fazit: Steppdecken in einer Lenzing Lyocell Wasserdampfdurchgangsindex imt (ISO11092) FILL / Polyester - Mischung können sowohl herangezogen, wobei höhere Werte bessere industriell als auch im Haushalt problemlos Durchgangswerte bedeuten. Abbildung 7 zeigt gewaschen werden, behalten weitgehend einen dazu die Werte typischer Steppdeckenfüllungen. angenehmen Griff und zeigen zudem optimale Untersucht wurden Vliese kommerziell physiologische Eigenschaften. erhältlicher Steppdecken.

Komfort – Physiologie 0,6

Die ursprüngliche Aufgabe einer Steppdecke, die 0,5 Wärmeisolation, wird im wesentlichen von allen mt Produkten erfüllt. Moderne Heizsysteme und damit ausgeglichene Raum-Temperaturen im 0,4 Schlafzimmer (auch im Winter) relativieren die Wichtigkeit diese Eigenschaft. Beachtenswert ist 0,3 CLY 50% CLY Wolle Daune PES aber die Tatsache, dass der menschliche Körper FILL / 50% während des Schlafes durchschnittlich 0,4 l PES Feuchtigkeit abgibt, wobei der Großteil in Form von „insensiblen“ Schwitzens als Dampf über die Abb. 7. Wasserdampfdurchgangsindex imt. Körperoberfläche abgegeben wird. Der Schlafkomfort wird daher entscheidend durch So wie beim Wasserdampfdurchgangsindex das Feuchtigkeitsmanagement der Bettdecke schneidet Lenzing Lyocell® FILL auch bei bestimmt. Dem folgend spielt die anderen physiologischen Parametern wie Feuchtigkeitsaufnahme des Füllmaterials und der Kurzzeitwasserdampfaufnahmefähigkeit (ISO- Feuchtigkeitstransport durch das Füllmaterial 11092) und Feuchtigkeitsausgleichskennzahl am eine wesentliche Rolle bei der Auswahl des besten ab, so dass Lenzing Lyocell® FILL als der Füllmaterials. Feuchtigkeitsmanager bezeichnet werden kann. Auch die Mischung von Lenzing Lyocell® FILL Feuchtemanagement mit Polyester zeigt nach wie vor hervorragende Im Schlafzustand ist der Feuchtigkeitstransport physiologische Werte. in erster Linie auf die Dampfphase beschränkt. Zusammenfassend kann gesagt werden, dass Daher ist vorerst der Abtransport der 100% Lenzing Lyocell® FILL hervorragende Feuchtigkeit und damit der Wasserdampf- physiologische Eigenschaften aufweist und wie transport durch die Bettdecke zu beachten. Dies zu erwarten, die Gebrauchswerte durch kann mittels des Wasserdampfdurchgangs- Beimischung von Polyester noch verbessert widerstandes eines Füllmaterials gekennzeichnet werden. werden. Als normierte Größe wird dazu der 55

Verarbeitungstechnologien Faserbällchen Für die Erzeugung von Faserbällchen für In Bettwaren finden zum überwiegenden Teil Bettwaren finden kommerziell zwei zwei Arten von Fasergebilden Einsatz. Diese Technologien Anwendung. Zum einen ist dies sind Vliese sowie Faserbällchen. Lenzing die Krempeltechnologie, bei der im Gegensatz Lyocell® FILL ist in beiden Anwendungen zur normalen Vliesbildung die Einstellungen einsetzbar und ist durch keine Technologie verändert wurden, so dass die Fasern gerollt und eingeschränkt. stufenweise zu Faserbällchen geformt und verfestigt werden. Mit dem Krempelverfahren Vlies sind Bällchen in 100% Lyocell sowie beliebige Die Vliesherstellung nutzt zum überwiegenden Mischungen möglich. Anteil die Krempel und entsprechende DiezweiteTechnologieistdas Vliesbildner, wie z.B. Kreuzleger. Diese Lufttumblingverfahren (Nowo /FIN - PCT WO Technologie ist extrem vielseitig einsetzbar und 99/36609; finnische Patentnummer: 105571) gestattet Lenzing Lyocell® FILL in einer welches auf einem Stator-/Rotorprinzip beruht. enormen Bandbreite von Grammaturen sowie in Die resultierende Luftströmung fördert und formt verschiedensten Mischungen herzustellen. die Fasern in lockere Gebilde, die zunehmend Die Verfestigung der Vliese ist unproblematisch kompakter und damit verfestigt werden. und kann mit allen bisher für cellulosische Die Charakteristik der Faserbällchen (Größe, Fasern üblichen Verfahren (Binder, Form) ist stark von dem Verfahren abhängig, so Vernadelung, etc.) durchgeführt werden. sind die Nowo Bällchen beispielsweise etwas Entsprechend dem Einsatz bzw. den angestrebten größer und voluminöser. Eigenschaften ist für das Vlies - die Vliesorientierung, Schichtung und in der Steppware - die Musterung und die Nahtabstände zu berücksichtigen, da es ansonsten zu Vliesbrüchen bzw. großflächigen Faserver- frachtungen kommen kann.

100% PES 70% PES / 30% Lenzing 40% PES / 60% Lenzing Lyocell® FILL Lyocell® FILL Krempelverfahren Lufttumblingverfahren

Abb. 8. Optik von Faserbällchen aus PES und PES / Lyocell.

Analog zu Füllkörpern in Vliesform ist die 70% PES, welche nach dem Krempelverfahren Bauschigkeit bzw. Bauschelastizität von hergestellt wurden, und 60% Lenzing Lyocell® Faserbällchen ein wichtiges Kriterium. FILL / 40% PES nach dem Lufttumbling- Entsprechend dem eingangs beschriebenen Test verfahren gemessen. wurde die Wiedererholung von Faserbällchen aus 100% PES, 30% Lenzing Lyocell® FILL / 56

Belastung Wiedererholung Einsatzgebiete und Zusammenfassung 14 12 ® 10 Lenzing Lyocell FILL und deren Mischungen 8 werden in kardierter Form in Steppdecken, als

cm 6 Faserbällchen primär in Kissen, als Füllmaterial 4 eingesetzt. Die Verwendung bei Polstermöbeln 2 ist derzeit in Erprobung. Auch als Auflagevlies 0 für Matratzen und Matratzenauflagen wird ® PES 30% CLY / 60% CLY / Lenzing Lyocell FILL bereits eingesetzt, so 70% PES 40% PES dass wir der Vision des Bettes aus Holz schon einen Schritt näher gekommen sind. Abb. 9. Wiedererholung von Faserbällchen aus PES und ® PES / Lenzing Lyocell FILL Das Eigenschaftsprofil von Lenzing Lyocell® FILL entspricht daher voll dem Trend: Die Bauschkraft der Faserbällchen unter- schiedlicher Mischungen von Lenzing Lyocell® • natürlicher Ursprung FILL mittels verschiedener • Reinheit Herstellungsverfahren ist durchaus mit 100% • PES Bällchen vergleichbar. Funktionalität hinsichtlich Feuchtigkeits- management • exzellente Gebrauchseigenschaften speziell in Kombination mit Polyester.

An dieser Stelle bedanken wir uns für die Kooperation bei Firma Hefel, Firma Wozabal und Institut Hohenstein. 57

TENCEL® NATURAL STRETCH

Tom Burrow, Bob Morley

TENCEL Ltd., Spondon, Derby DE21 7BP, UK

TENCEL® woven fabrics with stretch are now What is needed to produce TENCEL® Natural being produced without the addition of any Stretch stretch fibres. This has been made possible as a result of the properties of the fibre and our To develop TENCEL® Natural Stretch three increased knowledge of the textile technology things are needed. The fabric must be that influences its behaviour. New dyeing and constructed so that it will allow crimp finishing routes have been developed to allow development. The fabric must be processed in the fabrics to be produced commercially. The such a way that the crimp is allowed to develop. stretch that is developed in TENCEL® Natural And when the crimp has developed, the fibres Stretch fabrics is a result of the way the fibres need to be set in order to make the stretch and yarns behave during wet processing. The permanent. If one of these three elements is yarns are crimped to such an extent that they missing, then the fabric may not have stretch provide the potential for the fabric to increase in properties; it may stretch but not recover; or the length or width. The crimp is set into the yarns stretch may not withstand repeated washing. giving good recovery from extension. Careful TENCEL® loomstate fabric design and appropriate finishing conditions are needed to give optimum stretch and recovery. TENCEL® Natural Stretch is a result of straightening of the yarn crimp within the fabric. High yarn crimp in the finished fabric gives outstanding stretch potential. More yarn crimp means more TENCEL® fabric stretch.

Fabric construction

If a fabric is required to stretch, then it must be constructed so that it can. The fabric construction Figure 1. Yarn crimp allows the fabric to stretch. determines both the total stretch of the fabric and the balance between warp and weft stretch. If a TENCEL® fibres and yarns are not easily fabric is to be designed to have weft stretch, then stretched under normal wear conditions. the loomstate fabric should be constructed so that TENCEL® fibre has a high fibre modulus and its loomstate width represents the stretched resists stretching. The extension at break for dry dimension of the final finished fabric. This is the fibre is typically 12 %. By using the TENCEL® same principle as is applied in producing stretch Natural Stretch route, fabrics can be produced fabrics with elastane. However, when a fabric is with up to 25 % stretch. woven with elastane, the width is pulled in as the TENCEL® Natural Stretch fabric is easy to fabric comes off the loom. With TENCEL® stretch allowing freedom of movement and Natural Stretch fabrics the width only reduces a garment comfort. When the load is removed small amount from the reed width. A loomstate there is rapid recovery of the original TENCEL® elastane containing fabric has some stretch fabric shape. TENCEL® Natural Stretch gives a properties. A loomstate TENCEL® Natural gentle stretch and not Power-stretch or Support- Stretch fabric has virtually no stretch. The stretch stretch. is developed during finishing. 58

Yarn crimp development crimp, the higher the stretch that can be developed. If there were a way to develop more Some yarn crimp is present in all woven fabrics, crimp, then it would be possible to increase the regardless of fabric construction. The properties amount of stretch. Because swelling of the fibres of TENCEL® allow the development of higher and yarns develops the crimp, then greater crimp levels of yarn crimp than is possible with other results from greater swelling. Caustic soda fibres. In most loomstate fabrics, yarn crimp is (sodium hydroxide) swells cellulose much more low and the yarns are in close contact with each than water does. The diameter of a TENCEL other at crossover points. Because there is no fibre increases by about 35% when it is wetted space between the yarns, there is little stretch in with water. But when a fibre is wetted with a the loomstate fabric. 10% w/v solution of caustic soda, the diameter Wetting of the loomstate fabric causes fibres and Figure 3 TENCEL® Yarn Swelling in Caustic yarns to swell in diameter. The fabric shrinks can increase by 300%. In a fabric, this level of because the TENCEL® yarns push each other swelling is not possible because there is apart as they swell and develop a crimped shape. insufficient space. The swelling potential TENCEL® yarns do not increase in length due to therefore translates into an increased force absorption of water. Neither do they extend making the yarns crimp. much under load because the fibre has a high modulus. Thus, all of the forces that are generated by swelling of the yarns are directed into increasing the yarn crimp.

Figure 3. TENCEL® yarn swelling in caustic.

To develop maximum stretch in a TENCEL® fabric, the fabric is treated with caustic and is allowed to relax. The amount the fabric shrinks is approximately equal to the amount of stretch that will be developed. When the caustic soda Figure 2. Fibre swelling in water: % increase in fibre solution on the fabric is washed out and diameter. neutralised, the fibres that make up the fabric are set into the shapes that they have at that time. At this stage the fabric still does not have stretch This gives the fibres a powerful memory of the properties. This is because the wet yarns are still unstretched dimensions of the fabric. When a in contact with one another so that there is no fabric has been treated with caustic soda in this space available at crossover points for the crimp way, the recovery from stretch is much greater. to be able to straighten. When the fabric is dried, The shape memory that is given to the fibres is the yarns retain the same shape as they had when not affected by washing of the fabric. The fibres they were wet. As a result, spaces develop have their memory because of hydrogen bonds between the yarns where they cross over. The formed within the fibre structure. While these fabric now has stretch . bonds could be broken by further treatment with a strong alkali, they cannot be broken by water Caustic setting alone. Thus, each time the fabric is wetted, and allowed to relax, it assumes the stable The amount by which a TENCEL® fabric will dimensions it was set at. stretch increases in direct proportion to the amount of yarn crimp. The higher the yarn 59

TENCEL® fibre properties The fabric specification needs to take account of this. The fabric needs to be woven to a width TENCEL® works exceptionally well in the corresponding to the stretched dimension Natural Stretch process because of its high fibre required. The final finished width then swelling and resistance to caustic treatment. corresponds to the unstretched dimension of the Natural cellulosic fibres do not swell as much as fabric. Because warp and weft yarn crimp are TENCEL® in caustic and hence crimp interrelated, increases in one may cause development is not so good. Some other man- reductions in the other. If the warp crimp is less made cellulosic fibres cannot be treated with this means that warp shrinkage has been reduced strong caustic solution and hence the swelling during wet processing. In order to achieve the cannot be generated. same picks/cm in the finished fabric, a slight TENCEL® fabrics give good recovery from increase in loomstate picks/cm may be stretch because the fibre is resilient. This is due necessary. The combined effect of these two to its high fibre stiffness (both dry and wet) that points is that the finished fabric metreage per helps TENCEL® fabrics to recover their shape. pick inserted in weaving remains unchanged TENCEL® fibre also has a high tensile modulus even though picks/cm may have been increased. (stiffness) both wet and dry. This stiffness means This is because the changes also mean that that TENCEL® fibres are not easily deformed shrinkage in fabric length is reduced. within the fabric and can more easily recover their original shape and position. The low Summary modulus of viscose means that it will easily stretch and distort and has limited capacity to TENCEL® can produce fabrics with a surprising recover. Other fibres tend to have an level of stretch and recovery without the need for intermediate performance. Despite the high synthetic or elastane fibres. Changes in tabric stiffness of TENCEL® fibre, TENCEL® fabrics construction can be used to provide the scope for are still soft. This is because of the space increased yarn crimp development and therefore generated within the fabric by the exceptional stretch where it is desired. Caustic setting is used TENCEL® fibre swelling. to swell the yarns to create yarn crimp and space in the fabric. This maximises fabric stretch as Construction economics well as enhancing recovery by setting the TENCEL® fabric. In order to develop weft stretch the fabric must be allowed to shrink in width during processing. 60

ONLINE QUALITY CONTROL OF VISCOSE BY MEANS OF IMAGE ANALYSIS

S. Jary

Lenzing AG, A - 4860 Lenzing, Austria

The behavior of solutions or melts during system of the production line. Viscose spinning and the characteristics of the continuously flows through the cell, the video resulting fibers are strongly dependent on the sequences are transmitted to a monitor or content of impurities. Impurities, such as computer. In order to transform the insufficiently dissolved raw material, dirt, or subjective pictures into an objective gas bubbles, lead to poor fiber strength or evaluation, we designed a special image even to a break-off during the regeneration analysis computer program. process. For this reason, regular testing prior Now we are able not only to analyze amount to spinning is necessary. and size of impurities of undiluted viscose, but Common particle measuring systems for also to differentiate between impurities of viscose solution quality control do not different types by means of an on-line system. distinguish between types of impurities, they are off-line, or the viscose has to be further Keywords: viscose, particle measurement, diluted. Therefore, we developed a image analysis videomicroscope device. It is possible to integrate this apparatus directly into the pipe ______

Introduction The COULTER device consists of two electrodes and a tube, which has an opening. The assembly Quality control of viscose solution concerning dips into an electrolyte (e.g., NaOH). Resistance impurities is very important with regard to fiber is measured and recorded continuously. Particles, properties: High particle content leads to low which pass the opening and are not of similar fiber strength or even to break-offs and, thus, bad conductivity as the environment, cause a change spinning performance. in impedance according to their three- The two most common methods for viscose dimensional size. However, the opening tends to evaluation regarding to particle content are block very easily and gas bubbles are detected as working by particles as well. • changes of impedance ("COULTER") or • light blockade (e.g., PAMAS), respectively: Particle detection via principle of light blockade

Particle detection by impedance measurement

Figure 2. Principle of particle detection by light blockade Figure 1. COULTER principle. (Source: GIT Labor-Fachzeitschrift 5/2002). 61

The device – in this case – consists of a light source, a tube, where the medium to be measured is led through, and a detector. If a particle passes the light beam, the detector gives a signal, which is proportional to the diameter. On this basis, particle volume is calculated. Unfortunately, the result is falsified, if the shape of the object is not spherical. However, there exist several disadvantages for Figure 5. Videomicroscope. both methods: However, first trials of the prototype integrated • The viscose samples have to be diluted to in the production line's pipe system showed the avoid particle aggregation, necessity of some further improvements • there is no distinction between types of concerning focusing the camera and sealing the particles, and • cell. After realization, we were able to record no online-measurement is possible. well-focused video sequences of viscose solutions enlarged 200 times (Figure 6). Image analysis

Upon observing a drop of viscose under a long distance microscope (Figure 3), we had the idea of developing a suitable online method for viscose evaluation, based on image analysis.

1mm

Figure 6. Shoots of viscose. Figure 3. Viscose solution (microscopically enlarged). So we reached our first goals: The core of the videomicroscope assembly The possibility of: developed (Figure 4, Figure 5) is a cell, where • viscose is continuously passed through. A continuous control, camera equipped with tele-optics transmits the • online control, and video sequences to a monitor. • identification of gas bubbles and fibers. However, without a computer supported analysis, the system was still subjective. Our next objective was to find a suitable image analysis system to evaluate number and size of impurities. The software should be able to distinguish between particle types, and to identify deposits inside the cell.  Based on OPTIMAS we created a sophisticated Figure 4. Videomicroscope, schematically. macro program. Through several steps the shot is modified to enable a satisfying analysis. First, motion of the particles is eliminated (Figure 7): 62

Figure 9. Identification of objects. Figure 7a. Elimination of motion.

Then, stripes, caused by transformation of the analogous to the digital image are corrected by means of Fast Fourier Transformation (see also Figure 7 and Figure 8).

Figure 10. Classification.

During the period of a trial lasting several days, we checked the identification of deposits, which were built over night by almost stopping the flow through the cell. By comparison of several images, which are recorded and analyzed right before, the deposits are identified and excluded from analysis (Figure 11). Figure 7b. Stripe correction.

Figure 8. Difference in analysis of an uncorrected and a corrected image. Figure 11. Identification of deposits (black marked).

In the next steps illumination is corrected, the picture is binary coded leading to the Storing each image would soon lead to a identification of the individual objects (Figure 9). “overcrowded” hard disc of the server. The objects are classified into fibers, air bubbles, Therefore, we decided to export the results to a transparent, and non-transparent particles (Figure tiny text file. Images are stored too, when a set 10). limit of particles is detected. Common spread sheet programs can easily import the data allowing graphical evaluations. 63

Conclusion system guarantees full functioning during continuous operation. We were successful in developing an online method for viscose quality control, by means of which we are able to analyze undiluted viscose. By our specially designed software we obtain Acknowledgement number and size of impurities, there is a The author would like to thank the FEL group, distinction between particle types, deposits inside Lenzing AG, and Ulrich Hirn, IPZ, TU Graz, for the measuring device are detected, and our the good cooperation. 64

CONTRIBUTIONS TO THE FLUID MECHANICS OF VISCOSE SPINNING

Robert Kickinger

Johannes Kepler University, Department of Fluid Dynamics and Heat Transfer, Altenbergerstraße 69, A-4040 Linz, Austria phone: +43-70-2468-9778, fax: +43-70-2468-9783, e-mail: [email protected]

The viscose wet spinning process is an different spinneret designs by variation of the important industrial process with highly number, distribution and orientation of the complex physical and chemical interactions. holes on a spinneret surface with regard to Both media involved (spinning solution and hydrodynamic forces on the filaments and the spin bath) are fluids. Therefore, fluid gradient of sulfuric acid concentration. mechanics play an important role and are a key science for a better understanding and Finally, a CFD approach is applied for further process development. computing the flow and concentration fields of A new scientific approach, which combines sulfuric acid in an industrial filament the chemical and fluid mechanical aspects of production unit, in which hundreds of the viscose wet spinning process as well as thousands of filaments are produced theoretical and numerical methods of fluid simultaneously. mechanics, is presented: a theoretical model It is demonstrated that the proposed for single filament spinning considering the computer simulation model is an excellent tool chemical neutralization reaction, which is of for spinning process optimization, central process importance, is proposed. With improvement of fiber quality and this approach it is possible to successfully development of new spinneret designs leading predict the flow field, concentration profiles of to a better understanding of the complex sulfuric acid and sodium hydroxide in the mechanisms in viscose fiber spinning. bath and in the filament as well as the reaction front in the filament. Keywords: viscose wet spinning process, fluid A simulation model of filament bundles allows mechanics, forces on filaments, conjugate mass for the comparison and optimization of transfer, neutralization reaction .______

Introduction the sulfuric acid concentration and the breaking of individual filaments by hydrodynamic Annually, two million tons of man-made fibers shearing forces in the spin bath. are produced by the viscose wet spinning process Although the importance of a sufficient supply of worldwide. In this important industrial process a sulfuric acid, a uniform distribution of the acid number of highly complex physical and chemical concentration across the spinneret and a well- interactions, such as visco-elastic material controlled flow of the spinning bath is well behavior, solidification of the filaments in a known from an empirical perspective, the highly swollen state, complex chemical scientific basis for a description and modeling of reactions, interaction with hydrodynamic forces such phenomena is still rather poor. and associated filament deformations, take place. In this paper a rigorous scientific approach, During the production process spinning faults which applies theoretical and numerical methods leading to poor product quality can occur. The of fluid mechanics, is followed to investigate the main reasons for faults include the occurrence of flow field as well as associated hydrodynamic splinters and fused fibers due to insufficient forces on the filaments and the transport of regeneration because of an uneven distribution of sulfuric acid into the filaments. 65

In contrast to established models for wet ∂u ∂u ν ∂ ∂u (u + v ) = (r ) (2) spinning processes in the literature [11, 12] this ∂x ∂r r ∂r ∂r new approach considers the chemical neutralization reaction, which is of central for the axial and radial velocity components u importance in the viscose wet spinning process. and v of the velocity vector H æuö u = ç ÷ (3) A new model for single filaments è vø in the spin bath. The velocity boundary layer is The elementary problem of single filament defined as the region, where the spin bath moves spinning is discussed. The spinning solution, a with an axial velocity component of at least 1% non-Newtonian solution of cellulose xanthate in of the filament velocity, caustic soda is extruded through a spinneret into an acidic precipitation bath forming solidifying u > 0.01U. (4) filaments of regenerated cellulose (Figure 1, an explanation of symbols is given in Table 1 in the appendix). Coagulation of the viscose and Axial velocity profiles u(r) for different distances diffusion of the acid into the filament by x tothenozzle(spinneret)aregiveninFigure2. neutralization of the alkali and decomposition of the xanthate are the main reactions during spinning.

Figure 2. Axial velocity profiles.

As clearly visible in Figure 2 and displayed in Figure 9, the velocity boundary layer grows in Figure 1. Model for a single filament. thickness with increasing filament length x. Therefore the filament pulls an increasing The filament is pulled with velocity U through amount of spin bath with it, the longer it gets. the bath by the godet. Because of the movement To accelerate this increasing mass of spin bath in of the filament and due to viscous forces a flow the boundary layer a force is necessary. This is induced in the spin bath, as indicated in Figure force is the reaction force to the braking drag 1. Axial flow velocities are high in the vicinity of force on the fiber, which is given by the integral the filament (u=Uat the surface of the filament) of the surface shear stress, and decay with increasing radial distance to the F = 2πR τ dx, (5) fiber. D ò 0 W This flow field is a typical boundary layer flow and it is computed by solving the steady, laminar where this shear stress (on the surface of the and incompressible boundary layer equations [8] filament) is given by ∂u 1 ∂(rv) ∂u + = 0 (1) τ = ρν . (6) ∂x r ∂r W ∂r and 66

The surface shear stress is therefore determined for the mass fraction of H2SO4 in the filament by the flow field and its distribution along the ω1,whereΓ1 considers the consumption of filament length is given in Figure 3, where sulfuric acid due to the neutralization reaction: U τ = ρν . (7) 0 H SO + 2NaOH → Na SO + 2H O. (10) R0 2 4 2 4 2

The surface shear stress is negative because it is An equation similar to (9) is solved for the mass directed against the filament motion. It can be fraction of sodium hydroxide in the filament ω2. clearly seen, that the surface shear stress is The neutralization reaction (10) is considered maximum at the tip of the filament (at the transport controlled. spinneret hole), where the filament is most With this approach, the mass fractions of sulfuric sensitive because solidification has just started. acid and sodium hydroxide in the filament can be calculated as given in Figures 4 and 5. The reaction front, as it emerges through the moving filament, is given in Figure 6.

The mass flow density of sulfuric acid J(x) through the surface of the filament is given in Figure 7, where = ω ρ J 0 B0 U. (11)

The maximum mass transfer occurs at the tip of the filament directly at the spinneret hole, where the concentration gradient is maximum. The corresponding mass fraction of sulfuric acid in Figure 3. Filament surface shear stress. the bath at the surface of the filament is given in Figure 8. Its minimum value is at the tip of the Due to concentration gradients sulfuric acid is fiber and increases monotonically with filament transported into the filament diffusively and length. reacts with the sodium hydroxide in the filament. This again illustrates, that the critical point of the viscose wet spinning process is at the tip of the The mass flux density J(x), which is the mass of filament directly at the spinneret hole, where the sulfuric acid transported into the filament per surface shear stress and H2SO4 mass transfer are unit area over its surface, is on the one hand maximum, the sulfuric acid consumption is determined by the flow field and diffusion in the minimum and only a thin shell at the outside of spin bath, and on the other hand by diffusion in the filament is solidified. the filament. Therefore, this is a so called Because of the mass transfer of sulfuric acid into ‘conjugate mass transfer problem’. the filament, a concentration boundary layer Mathematically this can be described by (indicated in Figure 1), which is the region where diffusion/convection equations [1] ω < 0.99ω , (12) ∂ω ∂ω ∂ ∂ω ∂ 2ω B B0 B + B = 1 B + B develops around the filament. Due to the high (u v ) DB ( (r ) ) ∂x ∂r r ∂r ∂r ∂x 2 Schmidt number in the bath (8) ν Sc = ~ 250 (13) for the mass fraction of H2SO4 in the spin bath DB ωB and ∂ω 1 ∂ω ∂ 2ω this concentration boundary layer is of much U 1 = D ( 1 + 1 ) + Γ (9) ∂x 1 r ∂r ∂x 2 1 smaller scale than the velocity boundary layer (Figure 9). 67

Figure 7. Mass flow density of H2SO4 at the filament surface. Figure 4. Contours of H2SO4 mass fraction [%] in the range 0 < x < 4000 R0.

Figure 8. Mass fraction of H2SO4 in the bath at the Figure 5. Contours of NaOH mass fraction [%] in the filament surface. range 0 < x < 4000 R0.

Figure 6. Reaction front in the filament.

Figure 9. Thickness of boundary layers.

For an exact and efficient resolution of this small scale layer a combined theoretical and numerical methods, in particular the local non-similarity method [2, 9], is applied. 68

Figure 10. Configuration 1: in-plane velocity distribution [m/s].

Figure 14. In-plane forces on filaments (dots: individual values, diamonds: averaged values).

Figure 11. Configuration 2: in-plane velocity distribution [m/s].

Figure 15. Configuration 1: mass fraction of H2SO4 [%] close to the spinneret.

Figure 12. Configuration 1: pressure distribution [Pa].

Figure 16. Configuration 1: mass fraction of H2SO4 [%] in some distance to the spinneret.

The equations in the bath phase and in the filament phase are coupled at the phase boundary by relations for the mass flow density and chemical activity for sulfuric acid. Activity

coefficients of H2SO4 have been taken from [6]. The value of sulfuric acid concentration at the tip of the filament as given in Figure 8 is determined

Figure 13. Configuration 2: pressure distribution [Pa]. 69 by the analysis of a mass transfer contact presented here. The purpose of this analysis is to problem as described in [3]. clarify if spinning faults are caused by an In practice, the radius of the filament is not excessively low concentration of sulfuric acid. constant along its length because of filament The flow of the spin bath is primary driven by elongation due to the take-up force and because the moving filaments (through the action of of water release due to the chemical reaction. An viscous forces) and by a pump. The streamlines extension to a non-constant filament diameter in the spin tube colored by H2SO4 mass fraction based on a perturbation approach is given in [5]. are shown in Figure 17. The mass fraction of A discussion of the proposed approach in full sulfuric acid on vertical plane in the spin tube is detail can be found in [4]. given in Figure 18. Due to the enormous geometrical complexity Analysis of Cup Designs (hundreds of thousands of filaments) this simulation approach relies on modeling the Spinneret designs used in industrial wet spinning effects of small-scale structures on large scales machines consist of a multitude of spinneret (each of the cylinders in Figure 17 represents the holes, either directly punched on a full spinneret filaments emerging from a cup). plate in a certain manner or designed by assembling a group of smaller units ('cups' or 'eyes') to form cluster spinnerets. These cups are Summary and Conclusions usually designed by various heuristic grouping strategies, which are usually evaluated In this paper the viscose wet spinning process experimentally. has been investigated with an approach that Here, a rigorous scientific approach is proposed combines the chemical and fluid mechanical to evaluate different cup designs: the flow aspects. pattern as well as pressure and concentration The flow field, hydrodynamic forces on the fields in the spin bath as induced by different cup filaments, the neutralization reaction front in the designs are computed and evaluated with regard filament and the concentrations of sodium to hydrodynamic forces on the filaments and hydroxide and sulfuric acid in the filament and in sulfuric acid concentrations on the surface of the the spin bath have been calculated. filaments. It has been demonstrated that with this method Figures 10 and 11 show in-plane velocity spinneret configurations can be designed and distributions for two different configurations. evaluated with respect to hydrodynamic forces The pressure distribution in the spin bath is given onthefilamentsandthesulfuricacid in Figures 12 and 13. The pressure drop from concentration gradient in the spin bath. outside of the filament bundles to the center is Furthermore the effect of parameter variations higher for configuration 1. A comparison of (such as filament radius, spinning speed, spin hydrodynamic forces on the filaments is given in bath H2SO4 concentration, etc.) and their Figure 14, where the radial coordinate is the influence on the spinning process can be studied. distance of a filament to the center of the cup. In Although the presented investigations represent this flow regime viscous and pressure forces are some substantial progress in the understanding of approximately of the same order of magnitude. this complex process there remains a lot of work The mass fraction of H2SO4 in the spin bath is to be done. Possible further research on the displayed in Figures 15 and 16 for different viscose wet spinning process may deal with e.g. distances to the spinneret. A more detailed the modeling of more complex chemical discussion of the analysis of cup designs can be reactions, solidification effects, temperature found in [7]. differences, visco-elastic effects, multi-phase flow. Industrial Filament Production Unit An especially important fact seems to be the efficient description of hydrodynamic forces on As an example of an investigation of an the filaments and associated deformation (fluid- industrial filament production unit the analysis of structure interaction), because these have proven the flow and concentration fields in a spin tube is to be central issues for the spinning process. 70

Figure 17. Streamlines in the spin tube coloured by H2SO4 Figure 18. Mass fraction of H2SO4 [%] in the spin tube. mass fraction [%].

Acknowledgements Fibers', ASME PVP, Vol. 424-1, 199-210, Atlanta, USA, 2001. I am grateful to Lenzing AG, who has [4] Kickinger, R.: A Fluid Mechanics encouraged the successful submission of this Investigation of the Viscose Wet Spinning research to the Paul-Schlack-Award competition Process and of Ventilation and Dedusting in 2002. Systems, PhD thesis, Johannes Kepler University, Linz, Austria, 2001. [5] Kickinger, R.; Gittler, P. 'Velocity and References Concentration Boundary Layers on Spinning Fibers', Proceedings in Applied [1] Baehr, H. D.; Stephan K. Heat and Mass Mathematics and Mechanics 2002, 1(1), Transfer, Springer Verlag: Berlin, 343-344, Wiley: Berlin, Germany. Germany, 1998. [6] Lide, D. R., ed. CRC Handbook of [2] Chen, T. S. 'Parabolic Systems: Local Chemistry and Physics, CRC Press Inc., Nonsimilarity Method', in Minkowycz, Boca Raton, USA, 1997. W. J.; Sparrow E. M.; Schneider G. E.; [7] Mayr, P. Numerische und analytische Pletcher R. H., eds., Handbook of Untersuchung der Strömungsverhältnisse Numerical Heat Transfer, John Wiley & beim Viskosefaserspinnprozess,Master Sons Inc., New York, USA, 1988. Thesis, Johannes Kepler University, Linz, [3] Kichkinger, R.; Gittler, P. 'Boundary Austria, 2001. Layers with Mass Transfer on Spinning 71

[8] Schlichting, H.; Gersten, K. Boundary Appendix Layer Theory, Springer Verlag: Berlin, Germany, 1997. Symbol Description D diffussion coefficient of H SO in the bath [9] Sparrow, E. M.; Yu, H. S. 'Local Non- B 2 4 D1 diffussion coefficient of H2SO4 in the filament Similarity Thermal Boundary-Layer J surface mass flow density of H2SO4 Solutions', ASME Journal of Heat R0 filament radius Transfer 1971, 93, 328-334, . U filament velocity [10] Vermaas, D. 'Diffusion Processes in the r radial coordiante u axial bath velocity component Spinning of Viscose Filament', Textile v radial bath velocity component Research Journal 1962, 32, 353-363. x axial coordinate

[11] White, J. L.; Hancock, T. A. Γ1 reaction source term 'Fundamental Analysis of the Dynamics, ρ spin bath density Mass Transfer and Coagulation in Wet ν spin bath kinematic viscosity τ filament surface shear stress Spinning of Fibers', Journal of Applied W ω mass fraction of H SO in the filament Polymer Science 1981, 26, 3157-3170. 1 2 4 ω mass fraction of NaOH in the filament [12] Yarin, A. L., Free liquid jets and films: 2 ω mass fraction of H2SO4 in the bath hydrodynamics and rheology. Longman: B ω10 H2SO4 mass fraction of fresh spin solution = 0 Harlow, England, 1993. ω20 NaOH mass fraction of fresh spin solution ωB0 H2SO4 mass fraction of fresh spin bath Table 1. Nomenclature. 72

HIGH SPEED SPINNING OF VISCOSE FILAMENT YARNS

Martin Nywlt

ENKA GmbH & Co. KG e-mail: [email protected]

ENKA invested in the technology of high and shrinkage, are excellent. Also at speed spinning to be prepared for the various manifolded spinning speed, the special ENKA developments in the textile market. continuous spinning process shows the The continuous spinning process according advantages in product properties in the ENKA CHEV-technology can now be comparison to the Nelson-type technologies. operated at 500 m/min spinning speed. At this Further increase in spinning speed is limited speed, the production stability and the by mass-transfer in the yarn forming step and product properties are at an optimal level. the washing units. Technically, a spinning Especially the level and the constancy of all above 1000 m/min is possible, but ENKA sees important yarn properties, such as dye uptake no economical benefit at this high speed. ______

Introduction materials with natural origin were en vogue especially in Italy. The viscose technology is the origin of the In the years 1998 to 2000, we faced in Europe a man-made fiber industry. The current basic trend towards “TECHNO” materials, based on technologies were developed in the years 1950 polyamide and polyester. This trend leads to a to 1960. These technologies are known as further decrease of the viscose filament capacities • Spool process worldwide. In 2002, some recession and a weak • Pot – or centrifuge process demand in the US hit the total textile industry. • Continuous process. This situation already influenced the top textile industry and will surely have impact on the yarn For ENKA, it was the target to clarify the industry. potential of all of these technologies. The As a consequence, in the past 2 years, the viscose discontinuous processes are highly optimized. filament capacity worldwide decreased by more At our plant Elsterberg, the most modern spool than 30%. If the temporary weakness will last process was built in 1991 to 1993, by utilization longer, a further capacity reduction will take of all optimization potential of the individual place. process stages. This paper will show the options and possibilities of the continuous technology. Quality requirements for viscose filament yarns Target of the 5-year development was to improve the productivity by manifolding the The textile applications for viscose filament yarns process speed. have remained basically unchanged over the past decades. In the apparel segments, viscose filament yarns are used for crepe fabrics, knitwear, Current situation : viscose filament embroideries and yarn blends together with wool or synthetics. The development of the high-speed spinning For garment lining fabrics, viscose filament yarns process started at ENKA in the early 90s, a time are still the most favorable materials to get the of high demand for viscose filament yarns. A right fabric properties. first phase of restructuring was finished, 73

Dependent on the fashion cycles, these various is more restricted to the heavy deniers. ENKA segments are characterized by strong therefore divested the production plants based on fluctuations in demand. pot spinning and invested in spool technology in A successful yarn process for these markets has Elsterberg. to be designed for high flexibility to cover all these applications. The titer range has to cover all segments; the technical performance of the water yarns has to be suitable for these various textile-processing steps. For ENKA, which dryer serves all these textile segments, the basic yarn properties • Constant dye uptake, • Consistency in all physical properties, • Excellent mechanical processing properties have to be the premises for the high-speed yarn spinning process. In the current textile industry, winder where time to market is the ultimate requirement, product deviations influencing the processability or fabric characteristics are not tolerated. yarn Technical requirements for the high-speed spinning process

Based on the market demands, the technical requirements can be defined. Constant dyestuff uptake is achieved by constant skin-core relation and porosity. This washing field means constant process parameters, such as temperatures, concentrations, and residence Figure 1. Nelson and ENKA CHEV principle. time throughout all process steps. Excellent mechanical processability requires a low number of contacts of yarn and machine The Nelson and the ENKA CHEV technology are parts, high quality of the surface of yarn guides, both continuous processes with short production godets with a controlled drive and a time (Figure 1). The compact Nelson process safeguarded protection of the individual realizes the post-coagulation step and the yarn filaments in all process steps. washing with low space requirements. This results Basic tenacity and elongation is tuned by the in comparatively low investment costs. This spin bath and viscose solution parameters. benefit in investment leads to a weakness in parameter constancy during these process steps. Comparison of existing technologies Result is the broad variance in physical yarn properties and dyeing characteristics. The known processes can be divided into four The technical more sophisticated ENKA CHEV basic technologies. Spool and pot-processes are process has a parallel yarn treatment. The different both discontinuous types. For all the various washing steps are fully separated and can be steps (spinning, washing, drying and winding) operated at optimal conditions. As a result, the the optimal processing speed and parameters quality of the CHEV yarns is fully comparable to can be chosen. The disadvantage is the high the spool spun yarns. labor intensity and high processing times. Within these two discontinuous technologies, the spool process covers a titer range from 67 dtex to 660 dtex at top quality; the pot process 74

Development of high-speed spinning viscose Yarn Formation filament The principle of yarn formation had to be ENKA started the development of high speed developed according a totally new approach. The spinning to reduce the specific investment cost residence time for fiber formation is constant due of the CHEV process, which were clear higher to diffusion of acid into the filaments. A stagnant than for a Nelson process. The product portfolio spin bath similar to spool spinning allows only a had to cover the titer range from 40 dtex to 167 spinning speed of 150-200 m/min. At higher dtex at the established ENKA quality level. speed, the friction of bath to fiber is too high, so Especially the yarn shrinkage of max. 5 % was that the yarn will break. With a spinning tube to be kept beyond this limit. The target spinning according the CHEV technology, an increase of speed was defined as 500 m/min, which meant speed can be achieved. Here the limits are the risk a factor of 3 to 5 in comparison to the of turbulent flow of spin bath in the tube resulting established speed. in a kind of intermingling of the filaments. The only way, in our experience, to spin at 500 m/min Process principle for high-speed spinning or faster is the use of a free falling spin bath (Figures 2 and 3). In a continuous spinning process, the yarn speed in every step has to be identical. The Washing Process dimensions of each unit are determined by the necessary residence time. For a minimized The washing section gives the opportunity to investment and therefore the optimal increase the mass transfer to a high extent. The economics, the target is to reduce these diffusion barriers of the total filament bundle can residence times as much as possible. An be increased by opening this bundle. The target in alternative to operate the process steps of a the washing section is to limit the film diffusion at continuous spinning at different speeds was the filament. developed by Asahi. The high-speed yarn formation was followed by a low speed Drying Process washing, where the yarn was folded on a sieve belt. ENKA did not follow this process strategy Contact dryers can reach high heat transfer rates. due to our demands in quality and process Other drying technologies, such as convection or stability. microwave, do not have the efficiency. Here, The mass transfer mainly determines the component suppliers can offer an optimal residence times of the processing steps. The technology. time limiting mass transfer is of course different during coagulation, degradation of the xanthate, Pilot plant washing and drying. The first step, the chemical reaction, is a fast A pilot plant with a 100 t/y capacity, engineered neutralization of sulphuric acid and caustic. The by ENKA, was operated for 2 years. In this pilot reaction rate depends only on the acid diffusion phase, all important components were tested, to the reaction zone. The washing process is various yarn types were produced and processed only controlled by diffusion. The limiting mass according all typical viscose filament applications. transfer coefficients of e.g. sodium sulphate in The yarn titers 40 dtex up to 167 dtex could be cellulose and in the laminar film are constant. spun at 500 m/min. The higher deniers required a Drying is also a diffusion process where heat reduction in spinning speed due to the mass transfer and the diffusion coefficient of water in transfer limitations. For these yarn types, the cellulose are the determining items. Common typical ENKA product properties were reached. for these types of diffusion processes are the The process stability at high speed is much more limited possibilities for acceleration of mass demanding. Yarn tension control throughout the transfer. total process steps is a must, requiring a sophisticated and also robust control system of the godet drives. 75

viscose spinbath yarn

spinbath

yarn spinbath spinbath viscose FALLING FILM SPINNING TUBE ( CHEV ) SPINNING

Figure 2. Comparison of spinning.

Spinning Washing section according CHEV First hot air Second contact Winding section principle dryer dryer section falling film

Figure 3. Process scheme.

Limits of High Speed Spinning The increase in spinning speed by factor 4 shows the potential of the viscose technology, which has The major technical limit is mass transfer already a history of about 100 years. By this within the bulk phase of the individual development, the specific investment costs for a filaments and the mass transfer restrictions of continuous filament production based on ENKA´s film diffusion. An increase of spinning speed CHEV technology is favorable compared to the can be achieved by a proportional increase of Nelson technology. By implementing the • Falling film length advanced process, the investment costs would be • Number of washing elements economically attractive. ENKA is therefore • Number of drying rolls prepared for all possible market situations. with increasing speed, the process stability will become the determining limit. Yarn breaks are more difficult to control, the probability to restart the total machine after minor problems increases. According ENKA´s experience, the achieved 500 m/min spinning speed is the current optimum between efficiency and process stability. 76

NEW WET OPENER – SYSTEM BLOW DRYER BY LENZING TECHNIK

Hans Weber

Lenzing Technik, Lenzing AG, A – 4860 Lenzing, Austria e-mail: [email protected]

Introduction an opened fiber mat on the subsequent dryer, which can either be a drum dryer or a belt Being an innovative company, Lenzing Technik dryer. Moreover the following goals have to be (LT) has set itself the task of constantly fulfilled: observing the needs and trends in the market • Reduction of the investment costs compared place to be able to analyze solutions to to conventional solutions problems and modifications in good time, and • Reduction of the well-known high to be able to present these to individual and maintenance and repair costs potential producers. • Elimination of possible fiber This approach led to the development of the contaminations (lubricants, fats) new „Wet Opener – System Blow Dryer“ from • Capacity increase potential with a Lenzing Technik (Figure 1). This paper will replacement investment inform about this development and present At the very outset I would like to state that we details of the status of our development work. have reached these goals and are thus able to The goal was a device with simplified fiber offer a successful technical solution. opening, while maintaining the gentle treatment of the wet fiber with an improved formation of

Figure 1. Schematic of the wet opener- system blow dryer. 77

Description and mode of operation across the working width in the following dryer inlet. Well-known wet-spots are considerably The „Wet Opener – System Blow Dryer“ is a reduced whereby the dryer performance is more new and important device to open fibers after efficiently made use of in terms of an increase the aftertreatment. The fiber is still wet here in capacity. with a moisture content of around 105 % to 110 As shown in Figure 2, the transition of moisture % and in a state in which fiber damage can is carried out in a very short space of time. The easily occur by mechanical overstressing, since turbulent air control and efficient mixture with the fiber is difficult to open depending on the the fiber leads to rapid evaporation of the liquid type and the treatment. and in turn to drying of the fiber. This effect is In this new opener, the fiber is treated very utilized in the new „Wet Opener – System gently with only one mechanical opening part, Blow Dryer“. Since the fiber can be admitted in the opening device. The essential opening effect the wet state without any danger with a very is performed by the combination of the blown high temperature, a considerably high content air transportation and the opening device. It is of moisture can be evaporated at this stage in a well-known that the force requirement for highly economical manner. The very gentle opening of a wet fiber will decrease to the opening of the fiber is done in addition in only extent that the fiber loses the moisture, and the one equipment. The following dryers, risk of fiber damage by mechanical loads particularly in the exiting production lines, can decreases in the same course. The “Wet Opener thus have corresponding relief of their loads, – System Blow Dryer“ does justice to this which can be used for other efforts, such as realization. capacity increase. The use of a blown air device here is definitely nothing new to the fiber industry. However, the T, RH, HR fibre moist.[%] 120 use of this in the combination of a drying 110 T dry bulb system with a wet opener is new. [°C] rel. humidity [%] The amount of blown air required for fiber 100 transportation and drying is heated up via a heat humidity ratio 90 [g water /kgdry air] exchanger and applied to the wet fiber in a so- fibre moisture [%] called mixing chamber. This is then led via the 80 of pipe transportation fan to the actual opening device of pipe exhaust exhaust after fan after fan before fan before fan air suction air suction via an air separator. The heat exchanger can end end Fibre seperator Fibre seperator Mixing chamber either be heated with steam, gas or electricity. Mixing chamber The transportation fan used has to have a Figure 2. Temperature - fiber moisture diagram. special design for the task of transporting the damp fiber. In the air separator the transportation air is separated from the fiber and Features the fiber falls into a shaft where it is opened via the opening devise comprising the feed rolls Economic efficiency with regard to new and and the opening tambour. replacement investments. The system offers the A certain amount of moisture is important advantage of very economic specific correspondingly removed from the fiber as a costs to increase the performance of existing result of transportation via the ventilating fan production lines. The mechanically and and the feed. This simplifies the subsequent technically mostly mature dryer lines undergo opening of the fiber in the opening device quite an increase in capacity as a result of an considerably. integrated „Wet Opener – System Blow Dryer“. The spike conveyors used in conventional wet Thus, for the first time a very attractive piece of openers are no longer used here. The fiber equipment is available for production lines. opening is mostly equally as good, if not better, In the recent past in most cases only concepts than compared with the plants used until now. were developed for new production lines „on Another important advantage is an as a whole grassroots basis“ with very long financing better opened fiber, mixed homogeneously terms, thus making them difficult to finance. 78

Only a few producers have so far dared to Elimination of fiber contaminations. The modify existing production lines step-by-step, reduction of the moved and rotating mechanical since specific engineering and planning know- parts in the system and the use of corresponding how is required fort this to reach the materials sufficiently does justice to the modification goal without any risks and to requirement to prevent any possible product minimize the necessary production failures in contaminations (dirt, lubricants, etc.). the conversion phase. There were also hardly any systems available in the market, which Flexibility of plant layout. The conception of would have been of use to producers. The SXS the „Wet Opener – System Blow Dryer“ allows spinning technology from LT on a modular for a very flexible plant layout. The system basis already took a major step forward only a design makes it possible to install it as you wish short time ago. The innovation concept of LT is and thus save on building space. This advantage persistently continued with this new system. has economic consequences with regard to new Producers can thus increase their fiber capacity respectively replacement investments. simply and favorably without having to invest in a complete line. Modular System-Design and Plant Capacities. The modular system design selected makes it Low repair and maintenance costs. The possible to operate the different capacities of maintenance costs with this system have to be the plant in a very efficient manner. As a lower in view of the much simpler plant standard the common working widths of compared to conventional equipment: production lines are taken into consideration. • the number of mechanically moved parts is AsshowninFigure3,wehavealready very low, developed standardized calculation models so • the ventilating fans used and the piping is as to be able to calculate a customer-oriented insignificantly low from the viewpoint of capacity and layout very quickly. repairs • the air separator is quite safe with regard to the risks for repairs. Results to date

It should be taken into consideration that all Our experience to date has shown that the over the world in well-known production plants amounts of fiber produced were fully accepted the section of wet opening and the spike by customers in the down stream processing. conveyor have the highest specific repair costs. Thus apart from the examinations conducted in- Inadditionthesameareaisresponsiblefor house it is confirmed that the fiber quality most production failures. Until now this was produced is equally as good as that produced by money unwisely spent, causing a lower conventional lines or was even improved upon production availability. with regard to individual values. Moreover, the aim is to considerably reduce the A reduction in the fiber moisture level by more effort required for cleaning using the „Wet than 20% is achieved with a prescribed amount Opener – System Blow Dryer“ and to of air and heating capacity. A given dryer can significantly improve the efficiency of cleaning. be extended in terms of its capacity by the The accessibility of the equipment is simple and equivalent of this amount of water content or easy to accomplish. the fiber drying can be performed in a gentler manner. Opening device without the spike conveyor. The There is ample practical production experience new „Wet Feed & Blow Dryer“ is an opening with the wet opener part at our subsidiary in the device without a spike conveyor. Apart from USA and at the same time drying trials were the advantage already mentioned i.e. the successfully completed in production reduction in repair and maintenance costs they conditions. system fulfils the task of treating the fiber with care via mechanical work. This will also benefit the fiber quality. 79

WET OPENER - SYSTEM BLOW DRYER

by Lenzing Technik

humidity %: 70 CALCULATECALCULATE

surrounding air: production 50 temperature 24° C tons/day 60 realitive humidity % DRYING

511 kg water/h 24,5 %

dryerfeed heater

air temperature: 160° C airflow m3/h: 10.000

Figure 3. Cost calculations.

Summary Acknowledgement

The results we have received today I would like to warmly thank my coworkers for acknowledge our concept and have encouraged their commitment and active support during the us to march ahead with the marketing of our development phase of the new „Wet Opener – product. System Blow Dryer“ as well as for their help The new „Wet Opener – System Blow Dryer“ with this paper. from Lenzing Technik offers a definite alternative to the wet opening system used in numerous applications! There are already some attractive inquiries from interested parties and we are already negotiating with one of them. 80

QUANTITATIVE DETERMINATION OF CARBOXYL GROUPS IN CELLULOSE BY COMPLEXOMETRIC TITRATION

Lidija Fras,1 Karin Stana-Kleinschek,1 Volker Ribitsch,2 Majda Sfiligoj-Smole,1 Tatjana Kreze1

1 Univ. of Maribor, Inst. of Textile Chem., Lab. for Characterization and Processing of Polymers, Smetanova 17, 2000 Maribor, Slowenia fax: +386-62 220 7990; e-mail: [email protected] 2 University of Graz, Institute of Chemistry, Rheology & Colloid Science

Complexometric titration was used to of selectively oxidized fibers, twice as high as determine the carboxyl group content of a the content of carboxyls in raw fibers. The series of oxidatively treated (selective and carboxyl group content for non-selectively non-selective oxidation) nature cellulose oxidized fibers increased by approximately fibers (cotton). The results were correlated 180%, relative to untreated fibers. with those obtained from the conventional The results of our investigation demonstrate methylene blue method; both methods show clearly that complexometric titration is an an excellent correlation. The progress of the excellent tool for monitoring the influence of cellulose fibers oxidation was monitored chemical modifications on the carboxyl group using viscosimetric determination of the content. This method is sensitive enough to molecular weight. determine small changes in the content of The content of carboxyl groups depends on functional groups for chemically modified the oxidation procedure and it is, in the case fibers. ______

Introduction an alteration in the number and allocation of functional groups and possible degradation. The Cellulose fibers have a number of essential processing of cellulose has an influence on the advantages expressed by costumer friendliness fibrillar structure, i.e., the cellulose structure is in comparison to synthetic textile polymers loosened, causing swelling of the polymer and (PES, PA, PAC). Their main disadvantage is of increased accessibility of active groups on the technological nature, i.e., their finishing process fiber surface [1]. It is assumed that these is much more complex, and, therefore, modifications on the solid phase surfaces mainly environmentally aggravating. Although change the interaction ability of the cellulose finishing processes have been used for several fibers with components at the liquid phase. years, they are only partially understood, and The fine structure of the cellulose fiber is already better basic understanding is needed in order to quite well understood, contrary to the reaction gain some knowledge about their influence on abilities of the fiber surfaces, which is correlated fiber adsorption ability, hydrophilicity or the with the quantity and quality of the cellulose accessibility of active groups for the final fiber reactive accessible groups. It is extremely finishing as dyes or surfactants. important to be able to determine the number of During the production and processing of the accessible groups in order to judge the cellulose materials, chemical (oxidation and polymers’ interaction ability, their ion exchange hydrolysis) and structural modifications (degree capacity and the progress of technological of crystallinity and form of the unit cell) are processes during the manufacturing of cellulose applied in order to change the reactivity due to polymer materials. 81

Carboxyl groups in cellulose are able to act as correlation of the results of both methods should sources of ion exchange capacities [1] and can make it possible to assess which one is more be utilized to analyze the dissociation process in appropriate for the quantitative determination of heterogeneous polymer systems, the polymers’ carboxyl groups in cellulose. reactivity and the accessibility of these groups. The ion-exchange properties of cellulose fibers can, therefore, be used to monitor the quantity Experimental of carboxyl end groups, which is a matter of special importance in order to control the Natural cellulose fibers (cotton) were modified in progress of oxidation processes. different ways in order to judge the ability of the The amount of carboxyl groups present in the new approach to analyze the behavior of original material or created by oxidation can be celluloses after different chemical processes. They determined by different techniques [2-6]. were chemically modified by oxidation in order to Methods involving both paper and column obtain different contents of carboxyl groups. The chromatographic techniques were evaluated as oxidation of cellulose causes an increase of both to their suitability for measuring the ion- carboxyl and aldehyde groups depending on the exchange capacity of pulps and nitro pulps [2]. oxidation and the reaction conditions [1]. The spectroscopic methods and the method of Oxidation processes lead to degradation of the exchange with the base of crystal violet in a celluloses’ macromolecules exhibiting strongly non-aqueous medium have also been used [1,3]. modified material properties due to the reduction A few methods including titration for of the degree of polymerization [1]. The progress determination of carbonyl groups and acidic of the cellulose fibers oxidation was monitored by groups in cellulose pulps are shown in the viscosimetric molecular weight determination. literature review [4-5]. In this paper, we present a new method for Materials determining the amount of carboxyl groups in Natural cellulose fibers (cotton fibers Egypt Giza, cellulose fibers based on the ion exchange type Pirate: fiber length 35 mm, micronaire value reaction between calcium ions and carboxyl 4.1, regain 8.2 %) were investigated. groups. This method is a modified Sobue- Okubo method [6], based on a determination of a) Purifying treatments of cotton cellulose. The the remaining amount of calcium ions in the following purifying processes for the cotton solution after ion exchange with cellulose cellulose fibers were applied in order to obtain a fibers. Measurement of the decrease in cation well-defined reference substance: concentration of the added calcium acetate Boiling-alkaline cleaning (NaOH). Removal of solution was performed using a standard non-cellulose compounds (hemicellulose, waxes, complexometric EDTA (ethylenediamine- pectin, proteins); 20 g/l NaOH, pH = 11.5, T = 95 tetraacetic acid) titration. The results of this °C, t = 90 min. method were compared with those obtained by Oxidative bleaching (H2O2). Degradation of the methylene blue method, where the natural dyes and pigments; 9.5 g/l, 35 % H2O2,pH methylene blue dye cations bound to the = 11.2, T = 95 °C, t = 30 min. cellulose carboxyl groups were monitored Demineralization (HCl cleaning). Removal of all spectrophotometrically. non-cellulose components (cations); 0.1 M HCl, T Both methods, the methylene blue and the =20°C, t = 2 h. complexometric titration, are based on the ion After each treatment the fibers were washed with exchange capacity of the cellulose. A distilled water until a conductivity of less than 82

3mS/m was reached. The processed material Analytical methods was air-dried. Pre-treated cellulose fibers were chemically modified by oxidation. Titration method. An air-dry sample equivalent to 0.5-1.0 g was weighted into a 200 ml glass- b) Oxidation of cellulose fibers stopper flask. 100 ml of calcium acetate solution Selective oxidation. Purified (according to the were added. The flasks were shaken overnight, description under “a”) cellulose fibers were and then the suspension of fibers was filtrated [1]. first oxidized with 0.01 M KIO4 at 20 °Cfor6h A suitable volume of filtrate was pipetted into a and 24 h to form aldehyde groups at C2-C3 [1]. beaker and the color indicator murexide was During the following process step, chlorite (III) added as a metalchromic indicator. The pH value selectively oxidizes the aldehyde groups to of the filtrate was adjusted to 12 by the addition of carboxyl groups [1]. The fibers were, therefore, 0.1 M sodium hydroxide solution. The decrease in treated with solutions of sodium chlorite (0.2 concentration of calcium acetate solution after M) for 24 h at 20 °C under acid conditions at contact with the fibers was determined using an pH = 6 (100 ml of oxidation reagent per gram automated titrator Mettler Toledo DL 53. 0.1 M of fiber). EDTA solution was used as a titrant Non-selective oxidation: fibers were oxidized (standardization against zinc sulfate). The with 0.1 M HClO4 for24hand48hat20°C equivalence point was indicated photometrically (100 ml of oxidation reagent per gram of fiber). using a Mettler Toledo DP 660 phototrode, which measured the absorbance of the solution after each The oxidized fibers were washed with distilled addition of titrant volume (V) and, therefore, color water to constant conductivity and dried in air. changes at the equivalence point were perceived The fiber bundles were taken apart to single automatically as well as visually. The process was fibers prior to the titration. Table 1 gives an observed using a potentiometric unit. The overview about the applied chemical treatments equivalence point was determined from the of cotton cellulose fibers. classical titration curve E = f(V) by non-linear regression analysis [7]. The carboxyl group content of the cellulose sample is obtained according to:

Treatment of cotton cellulose fibers Sample Type of treatment (Egypt Giza 86, type Pirate) Pre-treated (alkaline boiling and oxidative bleaching) and de- A Purification mineralized fibers Sample A was oxidized by 0.01 M KIO , T = 20°C, t = 6 h and B 4 Selective oxidation then treated with: 0.2 M NaClO2, T = 20°C, t = 24 h, pH = 6 Sample A was oxidized by 0.01 M KIO , T = 20°C, t = 24 h and C 4 Selective oxidation then treated with: 0.2 M NaClO2, T = 20°C, t = 24 h, pH = 6 Sample A was oxidized using: Non - selective D 0.1 M HClO4, T = 20°C, t = 24 h oxidation Sample A was oxidized using: Non - selective E 0.1 M HClO4, T = 20°C, t = 48 h oxidation T = temperature of treatment [°C], t = time of treatment [hours] Table 1. Chemical modification of cellulose fibers 83

(V −V )⋅ C ⋅ f ⋅1000 (sodium salt of ferric tartaric acid) according to COOH = eqb eqa m (1) standard DIN 54 270 [9-11]. The viscosity [mmol / kg] measurements were performed in a modified Ubbelohde viscometer (capillary length 78 mm, where V is the consumption of titrating eqa capillary diameter 0.75 mm, 0.7 cm3). The reagent (EDTA) for the sample [ml], V is the eqb intrinsic viscosity [η] was calculated from the consumption of titrating reagent (EDTA) for efflux time of the cellulose solution (t), the the blank value [ml], C is the concentration of blank EWNN solution (t0), and from the the titrating reagent [mol/l], f is the factor of the concentration of cellulose in solution (c) titrating reagent, and m represent the weight of according to the Schulz-Blaschke equation [12]: sample [g]. All presented values are the mean ()η −1 / c []η = rel (3) value of 5 parallel measurements. + ⋅ ()η − 1 kη rel 1

Methylene blue adsorption. A weighted where ηrel is the relative viscosity and kη is the cellulose sample (approx. 0.5 g) of known coefficient for a given polymer solvent system water content was suspended in 25 ml of (0.3 < kη > 0.4). The degree of polymerization aqueous methylene blue chloride solution (300 (DP) was calculated according to Kuhn, Mark, mg/l) and 25 ml of borate buffer of pH = 8.5 for Houwink [13]: 1hat20°C in an 100 ml Erlenmeyer flask and α 1 DPη = ⋅ []η (4) then filtered through a sintered-glass disk. 5 or K p 10 ml of the filtrate were transferred to a 100 -3 ml calibrated flask. Then 10 ml of 0.1 N HCl where Kp =3310 [dl/g] and α = 0.74. and subsequently water, up to 100 ml, were added and the methylene blue content of the liquid was determined photometrically, Results and discussion employing a calibration plot. The total amount of free, i.e. non-adsorbed, methylene blue was The values of the carboxyl group content calculated from experimental results (A) [8]. obtained by the titration technique for different Applied analytical equipment: Perkin chemically modified samples are presented in spectrophotometer, Elmer Lambda 2 UV/VIS. Table 2 and compared with the values obtained The carboxyl group content of the sample is using the methylene blue method. obtained according to [8]: Titration Methylene Sam CV CV method blue method ()7.5 − A ⋅ 0.00313 ple [%] [%] COOH = [mmol/kg] [mmol/kg] E (2) A 12.81 2.28 43.26 0.27 [mmol / g] B 21.36 2.50 48.25 0.31 where A is the total amount of free methylene C 26.91 4.75 50.44 0.50 blue [mg] and E is the weight of oven-dry sample [g]. All presented values are the mean D 32.10 4.20 54.0 1.10 value of 5 parallel measurements. E 39.64 6.92 57.50 0.2

Viscosimetric determination of the degree of Table 2. Carboxyl content of chemically modified cotton polymerization. The degree of polymerization fibers measured using titration method and methylene blue method; CV is coefficient of variation was determined viscosimetrically after dissolving the cellulose samples in EWNN 84

The reference material A (purified) has a Selective Oxidation (Figure 1) carboxyl group content of 12.8 mmol / kg As discussed before, aldehyde groups are obtained by complexometric titration and 43.26 formed during the first step of selective mmol / kg –COOH groups obtained by the methylene blue method. The differences in the oxidation at the C2-C3 positions, and in a absolute values obtained using complexometric second reaction step these aldehyde groups are titration and spectrophotometric determination oxidized to carboxyl groups. An increase in the will be discussed in detail later. The ion -COOH group content determined using exchange capacity of the fiber increased after complexometric titration was observed in the oxidation processes due to increased samples B and C, which were selectively quantity of carboxyl groups. An evaluation has been made about the effect of oxidation time oxidized to the aldehyde groups in 0.01 M KIO4 and reagent concentration on the oxidation medium for different periods of time (sample C process. was oxidized 18 hours longer than sample B). Further oxidation to carboxyl groups was Carboxyl groups in selective oxidized fibers 60 carried out during the same time (24 h) at a

50 concentration of 0.2 M NaClO2. The carboxyl

40 group content of sample B (mmol / kg) has

[mmol/kg] 30 almost doubled compared to the reference 20 sample A. The carboxyl group content of COOH 10 sample C is 26 % higher than that of sample B, 0 which is a consequence of the higher amount of ABC Samples of chemically modified fibers aldehyde groups gained in the first process step

complexometric titration spectrophotometric determination (increased treatment time: 24 h instead of 6 h). It is also difficult to determine whether all Figure 1. Carboxyl group content in selectively oxidized fibers (B, C). reducing groups in the cellulose have been oxidized to carboxyl groups. Figure 1 and Figure 2 show comparisons of the carboxyl group content for selectively and non- Non-selective oxidation (Figure 2) selectively oxidized fibers, which were Under conditions of non-selective oxidation determined using complexometric titration and (treatment with 0.1 M HClO4) the carboxyl methylene blue methods. group content of fibers increased from 12.81 to 32.10 mmol / kg (D) in 24 hours, and to 39.64

Carboxyl groups in non-selective oxidized fibers mmol / kg (E) after 48 hours. The content of 60 carboxyl groups in sample E (which was 50 oxidized for 48 hours) is about 23 % higher in 40 comparison with fibers oxidized for 24 hours 30 [mmol/kg] (sample D). The increase of the carboxyl group 20

COOH content is more pronounced by non-selective 10

0 oxidation in comparison with selective ADE oxidation. On average a 50 % higher number of Samples of chemically modified fibers complexometric titration spectrophotometric determination –COOH groups is observed compared to the values obtained by selective oxidation, where Figure 2. Carboxyl group content in non-selectively the oxidation mechanism is known. Using non- oxidized fibers (D, E). selective oxidation, any possible oxidation product may occur because the course of the oxidation process is unpredictable. A mixture of 85 products is present, oxidized to different carboxyl groups is lower than the affinity of degrees and according to different mechanisms. methylene blue dye cations [16]. The degree of chemical modification of b) Another explanation for the higher values of cellulose polymers depends on the reagent the methylene blue method is that fibers can concentration and treatment time, which is also react in two ways with the dye cations. Besides confirmed by literature data [1]. The monofunctional reaction of methylene blue dye spectrophotometric methylene blue method cations with carboxyl groups of cellulosic shows the same absolute tendency of those fibers, interactions with hydroxyl groups are results at higher values (Table 2). also possible [1]. A study of the reaction mechanisms of dyes with cellulosic fibers Comparison of both methods indicated that the majority of interactions are The results of –COOH groups content obtained hydrogen bonds, not ionic bonds [17]. by both methods (complexometric titration and spectrophotometric determination) indicate a 70 E severe discrepancy. The carboxyl group content 60 D B C determined by the methylene blue method is 50 A almost twice as high as that determined by the 40 titration method. When seeking an explanation 30 for these differences several assumptions are 20 possible: Spectrophotometric method 10 a) The interpretation of carboxyl content 0 determination in cellulose by the Ca2+ exchange 12 17 22 27 32 37 42 Titration method method is difficult due to the fact that stoichiometry is unknown. Two reactions of the Figure 3. Correlation between methylene blue and divalent ions with carboxyl groups are possible titration methods. [14-15]: The systematic error of the methylene blue RCOOH + CaX2→ RCOOCaX + HX (5) method can be calculated by extrapolating the regression line in Figure 3, and amounts to 36 R(COOH)2 +CaX2→ R(COO)2Ca+2HX (6) - mmol / kg. It can be concluded that this amount X=CH3COO of dye was non-specifically adsorbed (without In reaction (5), one calcium ion is bound per interaction with carboxyl groups) at other carboxyl group. In reaction (6), one-half accessible places in the non-crystalline region calcium ion is bound per carboxyl group and, of the polymer. The smaller relative increase of therefore, a lower content of carboxyl groups is –COOH content determined by the methylene perceived in comparison with one-valence blue method after oxidation processes is binding of dye (methylene blue) cations to observed due to the larger systematic error. The carboxyl groups [1]. Mixed reaction types for methylene blue method is, therefore, less the carboxyl groups content might also be sensitive for monitoring changes of carboxyl possible, which is between both limit values. groups after oxidation processes, which is Regarding the literature [1], the results of confirmed by the slope of the correlation methods based on monofunctional reaction function (n = 0.5376 < 1) between titration and mechanism may give the same values as spectrophotometric methods. It can be methods based on bifunctional reaction concluded that a bigger systematic error is 2+ mechanism. The affinity of Ca ions toward obtained using the methylene blue method, but 86 a larger random error using the titration The oxidation processes lead to an increased method. The less perfect repeatability of the content of carboxyl groups as well as to a titration method may be caused by the cleavage of 1,4-β-glycosidic bond giving following facts: shorter polymers chains. The literature states • possible non-specific adsorption on the fiber that oxidation with chlorites causes cleavage of surface, polymer chains (Figure 4) giving new carboxyl • very low concentration of calcium acetate in end groups, which is confirmed by our results the solution – large experimental error, in the case of samples B, and C (Figure 5). • quality of the water used during the

processing operations (small amounts of 2400 45 40 different ions present in the distilled water 2000 35 causes lower ion-exchange values, because 1600 30 25 the fibers are incompletely turned into the DP η 1200

20 [mmol/kg] protonated H-form using this water), 800 15 • 10 atmospheric CO2 interferes with the 400 - COOH 5 determination (carbonate error). 0 0 Nevertheless, an excellent correlation between ABC Selective oxidized fibers samples both methods is evident in spite of the different average degree of polymerization carboxyl groups content absolute results achieved (Figure 3). The correlation coefficient between both methods is Figure 5. Degree of polymerization of selectively oxidized fibers (B, C). approximately 1.

Sample B gives a six times lower value of DPη Molecular structure changes (365) and sample C gives a seven times lower Chemical modifications of fibers also cause value of DPη (290) than the untreated sample A changes in carboxyl end groups and in the (2117), respectively. On average the DPη of the average degree of polymerization ( DPη ). selectively oxidized fibers (samples B and C) Precise information about products and reaction decreased by about 90 % regarding the mechanisms among oxidation procedure can untreated sample A, and simultaneously the only be gained with a combination of both carboxyl group content increased by 88%, methods (complexometric titration for which indicates a direct relationship between determination of –COOH groups and the reduction of DPη and the increase of the viscosimetric determination of DPη ). The carboxyl group content. The DPη of sample C results of determining the degree of decreased by a further 10% regarding sample B polymerization using the viscosimetric method due to an 18 h longer oxidation time in the first are given in Table 3. phase of selective oxidation, which gave higher –COOH group content and more intensive Sample η DPη CV [%] [ ][ml/g] cleavage of 1,4-β-glycosidic bonds. Acid non-

A 954,2 2117 4,82 selective oxidation with 0.1 M HClO4 does not B 259,6 365 1,60 cause the cleavage of 1,4-β-glycosidic bonds, C 219,2 290 2,31 and no reduction in chain length occurred. This D 990,8 2228 3,2 indicates a mechanism of carboxyl end group E 1014,7 2301 2,92 formation with oxidation on C6 (Figure 6). Table 3. The results of determining the intrinsic viscosity [η] and degree of polymerization DPη using the viscosimetric method, CV is coefficient of variation. 87

CH2 OH CH2 OH CHO CHO COOH COOH O O O O 1 4 1 4

O O O CHO CHO O O COOH COOH O CH OH CH2 OH 2 n n

Figure 4. Schematic presentation of the mechanism of cellulose oxidation by chlorite (III)

CH2 OH OH COOH OH O O O O 1 4 1 4 OH OH OH OH O O O O O O OH OH COOH CH2 OH n n

Figure 6. Schematic presentation of the mechanism of carboxyl end group formation with oxidation at C6.

Therefore, the DPη values of non-selective comparison with non-selectively oxidized oxidized fibers are only slightly higher (on fibers, selectively oxidized fibers show lower average by about 7 %) than the DPη of the content in these groups (mechanism of untreated sample (Figure 7). These minor oxidation). The methylene blue and the titration differences can be due to random or systematic methods used for carboxyl group determination errors. in oxidized fibers are in excellent correlation. Complexometric titration is due to lower 2400 45 systematic error and higher sensitivity more 40 2000 35 appropriate for carboxyl group content 1600 30 determination than the spectrophotometric 25 DP η 1200

20 [mmol/kg] method, which is recommended as a 800 15 10 comparable method to confirm any tendency of

400 - COOH 5 results obtained by complexometric titration. 0 0 ADE The results of this investigation demonstrate Non-selective oxidized fibres samples quite clearly that complexometric titration is an average degree of polymerization carboxyl groups content excellent tool for monitoring the influence of Figure 7. Degree of polymerization of non- selectively chemical modifications on the functional group oxidized fibers (D, E) content. When the results of carboxyl group determination and the viscosimetric Conclusion determination of DPη are compared, the following conclusions can be drawn: (a) the The influence of chemical modifications on the DPη of selectively oxidized cellulose fibers is ion exchange properties was studied, which is decreasing equally with the increasing –COOH linked with the number of carboxyl groups. content, and (b) non-selective oxidation in an Oxidation of cellulose fibers causes an acid environment gives carboxyl groups at C6 increased amount of carboxyl groups. In (from –CH2OH). 88

References [9] DIN 54 270: Bestimmung der Grenzviskosität von Cellulosen. Teil 1: [1] Browning, B. L. Methods of Wood Grundlagen. Chemistry. Interscience Publisher: New [10] DIN 54 270: Bestimmung der York, 1967. Grenzviskosität von Cellulosen. Teil 3: [2] Merill, A. M.; Schultz, J. S.; Saeman, J. EWNN Verfahren. F.; Tappi 1958, 41(10), 560. [11] Döcke, W. Prüfen von Textilen [3] Rebek, M.; Kirnbauer, A.; Semlitsch, Chemisch-Analytische Prüfverfahren. F.K. Das Papier 1960, 10, 510. VEB Fachbuchverlag: Leipzig, 1972. [4] Schleicher, H., Lang, H. Das Papier [13] Schulz,G.V.;Blaschke,F.J. Prakt. 1994, 12, 765. Chem. 1941, 158, 130. [5] Nevell, T. P. The Journal of the Textile [13] Krässig, H. A. Cellulose, Structure, Institute 1951, 42, 92. Accessibility and Reactivity. Gordon and [6] Sobue, H.; Okubo, M. Tappi 1956, 39, Breach Science Publishers: Switzerland, 415. 1993. [7] Mettler Toledo, Fundamentals of [14] Millet, A. M.; Schultz, J. S.; Saeman, J. F. Titration. Tappi 1958, 41, 560. [8] Klemm, D.; Philipp, B.; Heinze, T.; [15] Putnam,S.E.Tappi 1964, 47, 549. Heinze, U.; Wagenknecht, W. [16] Church, H. F. J. Soc. Chem. Ind. Comprehensive Cellulose Chemistry (London) 1947, 66, 221. Volume I, Fundamentals and Analytical [18] Drnovšek,T.PhDthesis,Universityof Methods. Wiley-VCH: Weinheim, 1998. Ljubljana, 2000. 89

DETERMINATION OF CARBONYL FUNCTIONS IN CELLULOSIC SUBSTRATES

Jürgen Röhrling,1 Antje Potthast,1 Thomas Rosenau,1 Herbert Sixta,2 Paul Kosma1

1 Christian Doppler Laboratory of Pulp Reactivity, Institute of Chemistry, University of Agricultural Sciences, Muthgasse 18, A-1190 , Austria

2 Lenzing AG, A - 4860 Lenzing, Austria

The reliable and accurate determination of chromatography. The method is applied as oxidized functionalities in cellulosic substrates pre-column derivatization and allows the still represents a largely unsolved problem in measurement of carbonyl profiles (plots DS cellulose chemistry. Aldehyde and keto vs. MW). Thus, the total carbonyl content and structures are “hot spots” along the cellulose the differential mass distribution of pulps can chain, where further chain cleavage might be determined. Practical aspects of the newly occur. Carbonyls are also relevant for developed method, a comparison of the processes such as yellowing or aging. approach to conventional methods, and Conventional approaches (copper number, different applications demonstrating the oxime or cyanohydrin method) provide sum general scope of the method will be presented. parameters only and suffer from limited Keywords: cellulose, carbonyl group comparability. In our approach fluorescence determination, carbonyl group profiles, labeling was chosen. Pulps are treated with a fluorescence labeling, gel permeation highly selective fluorescence label and are chromatography (GPC), CCOA method subsequently analyzed by size exclusion ______

Introduction Oxidized groups in cellulosics, such as keto and aldehyde groups,2 are introduced by pulping and bleaching processes, according to the Cellulose is the most abundant polymer from 3 renewable resources. While the chemical respective conditions chosen. Especially structure of the cellulose backbone does not seem bleaching – both chlorine-based and oxygen- to offer major challenges anymore, the based – is known to affect the integrity of the supramolecular architecture of cellulose and its cellulose backbone by generation of oxidized biosynthesis remain the prominent topics in positions and subsequent chain cleavage, which today’s cellulose research. However, cellulose is can be a result of both homolytic reactions, e.g. not only the “ideal” homopolymer, which is built attack of oxygen or oxygen-derived radicals, β up of anhydroglucose units linked by β-1,4- and heterolytic processes, such as - glycosidic bonds, it contains small amounts of elimination. The creation of oxidized groups various other, “irregular” structures, which are along the cellulose chain is thus a highly mainly oxidized groups. This applies especially undesired process, as these positions constitute to the material, which has undergone a number of "hot spots" along the carbohydrate chain, where process steps in the pulp and paper industries, a pronounced chemical instability is introduced and - albeit to a lesser extent - also to genuine, and where subsequent cleavage will primarily untreated cellulose. The reliable and accurate occur. Oxidized positions in cellulose are a determination of those oxidized functionalities in main reason for strength loss and decreased cellulose represented a largely unsolved problem performance parameters in textiles, paper and in cellulose chemistry.1 other cellulosic materials, they are chiefly 90 responsible for general aging processes of Materials and methods cellulosics,4 and are furthermore assumed to be the cause and promoter of thermal and light- GPC measurements used the following com- induced yellowing processes.5 ponents: online degasser Dionex DG-2410 and Gynkotek DG-1310, pumps: Kontron 420; puls The determination of carbonyls in cellulose has damper, autosampler HP series 1100, column to contend with several inherent difficulties. The oven Gynkotek STH 585; fluorescence detector extremely low average contents of carbonyls, TSP FL2000; MALLS detector Wyatt Dawn which range in the order of µmol / g, require very DSP with argon ion laser (λ sensitive means of detection since conventional, 0=488nm), RI direct instrumental techniques, such as IR, detector Shodex RI-71; Data evaluation was performed by the standard Chromeleon and Raman, UV, fluorescence or NMR spectroscopy, fail to report such minor amounts. Hence, a Astra software. For GPC measurements, the system as described by Schelosky et al.9 was chemical method must be applied, in which the carbonyl structures are either “titrated” by a modified, see Figure 1 for the experimental setup. DMAc / LiCl (0.9 %, m/V), filtered reagent, or converted in a suitable reaction into structures, which can then be monitored by through 0.02 µm filter, was used as the eluant. The sample was injected automatically, traditional spectroscopic techniques. chromatographed on four serial GPC columns Three conventional approaches to estimate the and monitored by fluorescence (exc. 290 nm, amount of cellulosic carbonyls are rather em. 340 nm), MALLS, and refractive index common: the copper number, applying copper (RI) detection. Molecular weight distribution (II) salts, which are reduced in turn and and related polymer-relevant parameters were 6 determined titrimetrically. According to the calculated by software programs, based on a 7 oxime method carbonyls react with hydroxyl- refractive index increment of 0.140 mL / g for amine, and the carbonyl content is reflected for cellulose in DMAc/LiCl (0.9 % m/V). instance by the nitrogen content as determined by elemental analysis. The third approach aims at converting the carbonyls into cyanohydrins by reaction with cyanide.8 All these approaches suffer from clear and distinct drawbacks, they are either based on conversions whose underlying mechanisms are far from being understood (copper number), they provide data which are only an indirect measure of carbonyls (copper number), or they suffer from strongly limited reproducibility (oxime and cyanohydrin method). In our approach, we started from two pre- Figure 1. Setup of the GPC system used. requisites: first, fluorescence spectroscopy was to be used as the reporting technique, as it is as a highly sensitive technique, which allows the detection even of smallest amounts of oxidized Results And Discussion structures. Second, the method to be developed should be implemented into GPC measurements Method development. The selection of the of cellulose (with fluorescence detection), and fluorophore in the fluorescence label depends thus not only provide the carbonyl content as a strongly on the conditions of the GPC sum parameter, but a carbonyl group profile in measurement. As MALLS (multi-angle laser relation to the molecular weight of the cellulosic light scattering) detection is indispensable, the material. fluorescent light must not interfere with this detection mode, which means that the difference between emission wavelength of the label and working wavelength of the laser used (λMALLS = 488 nm) should be as large as 91 possible. This is all but trivial, since most of the fluorescence emission maxima in this solvent. common, commercially available markers do not With the demonstration of the suitability of meet these requirements. CCOA as a fluorescence label for keto and In recent literature, O-substituted hydroxylamines aldehyde groups in low-molecular, oxidized have been described as structures for carbonyl sugar units under the conditions needed for the markers having increased reactivity as compared chromatography of cellulosics, the fundament to hydrazines.10 However, the fluorophores used, was laid for the labeling of carbonyl structures dansyl and rhodamine B derivatives, were also in macromolecular cellulosic materials. inappropriate, due to their emission wavelengths A complete derivatization is a prerequisite for interfering with MALLS detection. For that the quantification of carbonyl groups in pulp. reason, a novel carbonyl-selective fluorescence The derivatization procedure was optimized for label, which meets the requirements addressed a homogeneous solution in DMAc / LiCl (2.5 above, was synthesized in an expeditious three- %, m/V) and an aqueous suspension of the step approach as described previously.11 The pulps.13 In the homogeneous working procedure marker, termed “CCOA” according to its trivial the activated pulp was dissolved in DMAc / name carbazole-9-carbonyloxyamine, is based on LiCl (9 %, m/V), diluted to a LiCl content of the fluorophore carbazole, with its fluorescence 2.5 % (m/V), and finally subjected to labeling emission of 346 nm in DMAc / LiCl (0.9 % m/V) with CCOA. The pulp was precipitated with at an excitation of 290 nm being sufficiently water, thoroughly washed to remove excess remote from the working wavelength of the label, activated, and re-dissolved for GPC MALLS laser. As additional advantages, CCOA analysis. offers the reactive O-substituted hydroxylamine DMAc/LiCl structure as the anchor group, which binds to water carbonyls as an oxime, and carries an ethylene 40 glycol spacer that ensures the fluorescence characteristic to be independent of type and environment of the group labeled. 30

20 fluorophore spacer 10 carbonyl content [µmol/g]

O 0 N O O ABCDEFGH I JKLM N O NH2 H Figure 2. Comparison of the homogeneous and the anchor heterogeneous labeling procedure: overall carbonyl group contents determined. A: BS EO; B: BS Z1; C: BS Z2; D: BSZ3;E:BSZ4;F:BSZ1P1;G:BSZ2P2;H:BS R Z3P3;IBSZ4P4;J:BSZ4P5;K:BS;L:cottonlinters; "CCOA" M: eucalyptus PHK. Abbreviations: BS = beech sulfite, E = E stage (extraction), O = oxygen stage, Z = ozone abbrev.: R-O-NH2 stage, P = peroxide stage, PHK = prehydrolysis Kraft; Scheme 1. Structure of the fluorescence label carbazole-9- numbers reflect the intensity of the respective treatment. carboxylic acid [2-(2-aminooxy-ethoxy)-ethoxy]-amide, “CCOA”. As an alternative to the labeling in By means of model compounds, such as homogeneous phase, also the applicability of cyclohexanone as well as selectively oxidized heterogeneous labeling in aqueous media was carbohydrates as keto sugar models12 and tested. Heterogeneous derivatization would oligosaccharides with reducing end groups, it was circumvent the time-consuming and laborious demonstrated that CCOA reacts quantitatively removal of excess marker by precipitation and with keto and with aldehyde groups.11 All labeled re-dissolution of the labeled pulp, and thus model compounds exhibited identical allow much shorter times for analysis. 92

The optimized homogeneous and heterogeneous Analysis of the overall carbonyl content. The derivatization reactions were comprehensively ability of the CCOA method to determine the compared by evaluating MW and MN, the peak overall carbonyl content was used to monitor form of the fluorescence signal and the overall oxidative treatments of pulps. In the following carbonyl content. Both the heterogeneous and the some examples covering ozone/peroxide blea- homogeneous approach nearly produced the same ching and alkalization are given. values. This was demonstrated for a variety of different pulps, some examples are shown in figure 2. In some rare cases, the carbonyl content 60 3,0x105 determined in water ranged up to 10 % below the starting pulp ozone bleached (Z stage) 50 2,5x105 values determined by homogeneous labeling, ozone/peroxide bleached (ZP stage) which can be attributed to restricted accessibility 40 5 or inaccuracy problems in the respective sample. 2,0x10

30 [g/mol] 5 By comparing the MW and MN values of the non- 1,5x10 w M derivatized and derivatized pulps, it was shown, 20 that no chain degradation occurred during the 1,0x105 derivatization procedure. carbonyl content10 [µmol/g] 5,0x104 0 ABCDEFGH I J

starting pulp 5 60 4,0x10 Figure 4. Overall carbonyl content (bars) and MW ozone bleached (Z stage) (bullets) of a spruce sulfite (SS) pulp and a eucalyptus ozone/peroxide bleached (ZP stage) 3,5x105 50 prehydrolysis Kraft (PHK) pulp, measured along a 3,0x105 bleaching sequence with ozone and ozone/peroxide, 40 2,5x105 respectively. A: PHK; B: PHK Z1; C: PHK Z1P1; D: PHK Z2; E: PHK Z2P2; F: SS; G: SS Z1; H: SS Z1P1; I: 30 2,0x105

[g/mol] SS Z2; J: SS Z2P2. Abbreviations: Z = ozone stage; P = 5 w 1,5x10 M peroxide stage; increasing numbers reflect increasing 20 1,0x105 intensity of the respective treatment.

carbonyl content [µmol/g] 10 5,0x104

0 0,0 ABCDEFGH I J It was experimentally shown, that oxidative treatment of the pulps causes an increase in the Figure 3. Overall carbonyl content (bars) and MW (bullets) of a beech sulfite (BS) pulp, measured along a bleaching carbonyl content, as expected. In ozone sequence with ozone and ozone/peroxide, respectively. A: bleaching (“Z stage”), this increase was clearly BSEO;B:BSZ1;C:BSZ1P1;D:BSZ2;E:BSZ2P2;F: dependent on the ozone charge. A subsequent BS Z3; G: BS Z3P3; H: BS Z4; I: BS Z43P4; J: BS Z4P5. peroxide treatment (“P stage”), comprising Abbreviations: Z = ozone stage; P = peroxide stage; peroxide treatment and alkaline extraction, increasing numbers reflect increasing intensity of the respective treatment. decreases the carbonyl content in turn. This is due to oxidative transformations of carbonyl The heterogeneous labeling is advantageous over groups and extraction of carbonyl-containing the homogeneous method for several reasons: it lower-molecular weight material, as is well is completed at much shorter derivatization times, known from bleaching chemistry. Figure 3 recording kinetics is unnecessary, the presents the data of bleached beech sulfite precipitation – re-dissolution procedure becomes pulps, which had undergone different obsolete, and the results are as consistent as those treatments with either ozone (Z) or obtained according to the homogeneous working ozone/peroxide (ZP). Likewise, figure 4 procedure. The heterogeneous method (and only describes the bleaching of a spruce sulfite and a this one) thus clearly has the potential to become eucalyptus prehydrolysis Kraft pulp. Both a routine method in pulp and cellulose chemistry. figures clearly demonstrate that cellulose The heterogeneous method was validated and degradation, i.e. a DP loss, increases with applied in all following examples.14 increasing bleaching intensity, with ozone/peroxide combinations being especially critical. 93

25 treatments of cellulosics not only in terms of 5 3,0x10 the overall carbonyl content, but also with 20 2,5x105 regard to the carbonyl content relative to the molecular weight distribution. As the CCOA 2,0x105 15 labeling is actually a pre-column derivatization 5 1,5x10 [g/mol] procedure, the subsequent GPC analysis yields 10 W M 1,0x105 the carbonyl profiles for the respective samples,

5 and reports possible changes in these profiles carbonyl content [µmol/g] 5,0x104 caused by chemical treatments.16

0 0,0 ABCDEFGH I JK

Figure 5. Overall carbonyl content (bars) and MW (bullets) of a beech sulfite pulp, measured along alkalization (18% 0,020 NaOH, 42°C) along time. A: beech sulfite (starting 0,6 material), B: after steeping; C: 1 h; D: 2 h, E: 3 h, F: 4 h, G: 0,015 5h,H:6h,I:7h,J:8h,K:9h. 0,4 0,010 DS

Steeping and aging of cellulose are important dW/d(logM) 0,2 process steps in viscose fiber production. 0,005 Steeping is mainly aimed towards the removal of residual hemicelluloses, whereas aging leads to 0,000 0,0 appropriate pulp viscosities for further processing 1000 10000 100000 1000000 molecular weight (M) [g/mol] to viscose. Besides considerable changes in the molecular weight distribution during aging of Figure 6. Carbonyl DS and differential MWD of a beech alkali cellulose, also conversion of functional sulfite (BS), solid: unmodified, dashed: calculated MWD groups takes place. For the investigation of the for a mild degradation without changes in the shape of effect of alkali treatment towards the carbonyl the MWD. content, a beech sulfite pulp was treated with 18% NaOH. After pressing, the press cake was immediately shredded to provide an adequate In cellulose chemistry, the average degree of surface area for a uniform reaction. substitution (DS) denotes the number of Depolymerization kinetics at 42 °C was substituted OH groups per anhydroglucose unit; investigated. Samples were taken periodically it is most frequently used for cellulose esters or and analyzed (figure 5). The carbonyl content ethers. The DS thus reflects the completeness of decreased during the alkali treatment (steeping) a chemical modification at the hydroxyl groups by 50%. The carbonyl degradation slowed down of the polysaccharide. In the following, the term with increasing reaction time and leveled off at 4 “carbonyl DS” shall be used to describe the µmol/g. The main reason for the loss in CO average content of CO groups per anhydro- groups is progressing oxidation to carboxyl glucose unit.17 The typical decaying curve form functions.15 (figure 6) of the DS graphs results from the higher number of reducing end carbonyl groups Carbonyl group profiles. If only the overall carbonyl content of a cellulose sample is per anhydroglucose units in shorter chains. ∆ considered – as important as this value might be Especially DS plots, which give simply the – information is lost, since only a sum parameter difference between two DS curves, facilitate the is provided and possible differences between comparison of two samples with regard to their fractions of different molecular weight are carbonyl contents relative to the molecular leveled. Only carbonyl group profiles would weight. They allow, for instance, to analyze in a convey the full amount of information. With the very straightforward fashion, how a chemical CCOA labeling having been elaborated into a treatment increases or decreases the carbonyl general method, it became possible for the first content in certain molecular weight ranges. time to determine the result of chemical 94

DS or ∆DS plots on their own do not report A first example of the value of DS profiles is changes in the overall carbonyl content. For that displayed in figure 7, which delineates the purpose, the MWD must be considered. Already curves for ozone-bleached beech sulfite pulps. from the natural content of reducing end groups, With increasing bleaching intensity, the a DS can be expected for celluloses, which is carbonyl DS was increased for medium and decreasing with increasing MW. A shift of the high molecular weight regions, but dropped MWD towards lower molecular weight at below the value of the starting material for low constant DS curve shape yields a higher overall molecular weights. The boundary between DS carbonyl content (figure 6). This is caused by the increase and DS decrease ranged around an MW changed ratios of low-molecular to high- of 10000 – 20000 g / mol. Thus, the ozone molecular material, which are not considered for treatment is an interplay between carbonyl- DS or ∆DS curves. With MW degradation and a generating and carbonyl-consuming processes. simultaneous decrease in DS, the effects on the Such detailed descriptions of the carbonyl overall carbonyl content are oppositely directed. profiles would be impossible to make simply by An MW decrease causes an increase in overall the data for the overall carbonyl content. carbonyl content, a shift of the DS curve leads to Reducing end groups represent the major part a decrease in the overall carbonyl content. Thus, of the total amount of carbonyl groups in regarding only the overall carbonyl contents cellulose chains with a low DP. Upon ozone means a loss of information. treatment, these reducing end groups might be oxidized lactones and carboxylic acids, so that an ozone bleaching stage lowered the carbonyl 0,020 A 1,0 B DS in the lower molecular weight regions. In C cellulose chains with a high molecular weight, D 0,8 0,015 however, the contribution of reducing end

0,6 groups to the total amount of carbonyls 0,010 becomes much smaller, so that the oxidation of DS 0,4 reducing end groups is overcompensated by the

dW / d(log M) introduction of new carbonyl functions. The 0,005 0,2 generation of carbonyls predominantly into higher-molecular weight material might explain

0,000 0,0 the well-known observation that ozone- 1000 10000 100000 1000000 bleached pulps suffer a severe DP loss in a molecular weight (M) [g/mol] subsequent P stage: when the carbonyls 0,004 introduced upon ozone treatment are reduced DS ∆ ∆ ∆ ∆ by NaBH4, the pulp is rendered largely 0,002 insensitive towards the subsequent peroxide 18 0,000 treatment. With the pulp used, a very low ozone charge -0,002 BS Z2 - BS EO did not significantly increase the carbonyl -0,004 BS Z3 - BS EO content, since preferably the residual lignin BS Z4 - BS EO present in the material is attacked by the -0,006 oxidant.19 The progressing degradation of the polysaccharide material upon further oxidation, -0,008 as reflected by the decreasing MW, is clearly 10000 100000 1000000 visible in figure 7. molecular weight (M) [g/mol]

Figure 7. Carbonyl DS and differential MWD of a beech sulfite (BS) pulp after ozone-bleaching stages (Z). Increasing numbers reflect increasing intensity of the ozone treatment. A: starting pulp (BS EO); B: BS Z2; C: BS Z3; D: BS Z4. 95

0.030 1.0 A molecular weights, which shows the limitations B of this sum parameters with regard to a detailed 0.025 C 0.8 interpretation of the results. 0.020 A comparison of the graphs for the starting pulp 0.6 and the Z/P-treated pulp shows that this DP loss 0.015 DS occurs predominantly in the higher-molecular

dW / d(log M) 0.4 0.010 weight region: the differential MWD curves below a MW of 10000 g / mol are nearly 0.2 0.005 identical, whereas the curves above 10000 g / mol are shifted to lower values, cf. figure 8. 0.000 0.0 103 104 105 106 Thus, the degradation produces mainly molecular weight (M) [g/mol] fragments of a molecular weight larger than 4 0,002 10 . This interpretation is justified since the DS ∆ ∆ ∆ ∆ yield loss upon bleaching is only 0.5% so that 0,001 almost no material is lost. Thus, a chain cleavage occurs chiefly in the same molecular 0,000 weight ranges, in which carbonyl groups are introduced during the ozone treatment. In the -0,001 low MW range, which is only little effected by

-0,002 BS Z3 - BS EO the Z stage, also the chain degradation is small. BS Z3P3 - BS EO BS Z3P3 - BS Z3 Alkali treatment as performed in steeping and -0,003 aging during the viscose production causes a

-0,004 decrease in the total carbonyl content. The most 10000 100000 1000000 significant decrease (23.9 µmol / g to 13.6 molecular weight (M) [g/mol] µmol / g) in carbonyl functions takes place during steeping. From the MW distribution and Figure 8. Carbonyl DS and differential MWD of a beech sulfite (BS) pulp after an ozone (Z) and a peroxide (P) also from the carbonyl profile (figure 9) this treatment. A: starting pulp (BS EO); B: BS Z3; C: BS can clearly been attributed to the dissolution of Z3P3. low MW parts of the pulp. No change in the DS profiles occurred during this stage. The same trend continues to up to 1 h aging time where The effect of a peroxide bleaching stage is still no changes in the DS profile in the demonstrated in the figure 8: a standard beech cellulose polymer are observed. Between 1 and sulfite pulp was subjected to an ozone treatment 2 h the carbonyls at higher MW parts are followed by a peroxide bleaching stage. Again, it attacked as well, the drop between 10.3 to 6.9 is obvious that the initial ozone treatment µmol / g can now be observed for the polymer increased the carbonyl content at molecular backbone and not entirely be attributed to a weights above 20000 g / mol, and decreased it dissolution process of low MW parts. Already below this value. Also the DP loss is evident. The at 6 h the decrease in carbonyl groups levels subsequent peroxide stage has a quite beneficial off, no significant changes are observed as effect with regard to the CO content: in all compared to the final value. molecular weight ranges the carbonyl content is decreased as compared to the ozone-bleached material. Moreover, the DS profile fell even below the level of the unbleached starting material at molecular weights below 70000 g / mol, and ranged only slightly above the curve for the initial pulp above 70000 g / mol. Nevertheless, the overall carbonyl content was slightly increased from 25 to 30 µmol / g as a result of a shift of the MWD towards lower 96

starting material Acknowledgment 0,015 1,4 steeping 1h The authors would like to thank Dr. Sonja 2h 1,2 0,012 6h Schiehser for technical assistance, and Dr. 9h 1,0 Susanne Jary and Dr. Andrea Borgards for 0,009 0,8 preparing the samples of differently modified pulps. The financial support by the Austrian 0,6 0,006 Christian-Doppler-Forschungsgesellschaft and dW / d(log M)

DS 0,4 Lenzing AG, Lenzing, Austria, is gratefully 0,003 0,2 acknowledged.

0,000 0,0 10000 100000 1000000 molecular weight (M) [g/mol] References

0,005 [1] Klemm, D.; Philipp, B.; Heinze, T.;

0,000 Heinze, U.; Wagenknecht, W. Comprehensive Cellulose Chemistry;

-0,005 Wiley-VCH: Weinheim, Germany, 1998, steeping - starting material pp. 302-314.

DS 1h - starting material ∆ ∆ -0,010 ∆ ∆ 2h - starting material 6h - starting material [2] Included are also 1,2-dicarbonyls (-CO- 9h - starting material CO-), and dialdehyde groups. Carboxyl -0,015 groups (COOH), which have a much lower carbonyl reactivity, are explicitly -0,020 not covered in the following. 10000 100000 1000000 molecular weight (M) [g/mol] [3] a) See any text book of pulping and bleaching chemistry. b) Schleicher, H.; Figure 9. Carbonyl DS and differential MWD of a beech sulfite (BS) pulp after alkali treatment (steeping and aging, Lang, H. Das Papier 1994, 12, 765-768. 18% NaOH) with increasing reaction time. Treatment was c) Sixta, H. Habilitation thesis, Technical performedat42°C. University of Graz, 1995. [4] Lewin, M. Macromol. Symp. 1997, 118, 715-724.

Conclusions [5] See for instance: Beyer, M.; Bäurich, D.; Fischer, K. Das Papier 1995, 10A, 8-14. A novel analytical method for determination of carbonyl groups in cellulosics by heterogeneous [6] Tappi Test Methods 1989-1999, Tappi labeling with CCOA followed by GPC with Press: Atlanta, 1998, T430. fluorescence, RI and MALLS detection was [7] Green,J.W.InMethods in Carbohydrate developed. Already the overall carbonyl content Chemistry;Vol.3;WhistlerR.L.; is a valuable parameter to monitor the effect of Bemiller, J. N.; Ed.; Wiley Interscience: oxidative chemical treatments. Furthermore, the New York, 1973, p 49. method even provides carbonyl profiles relative [8] Lewin, M.; Epstein, J. A. J. Polym. Sci. to the molecular weight, which allow a much 1962, 58, 1023. more precise evaluation of oxidative changes. Evaluation of carbonyl profiles can conveniently [9] Schelosky, N.; Röder, T.; Baldinger, T. be done by means of “carbonyl DS” or “carbonyl Das Papier 1999, 53, 728-738. ∆ DS” plots. Industrial relevant processes, such as [10] a) Boturyn, D.; Boudali, A.; Constant, J. bleaching and alkalization were investigated and F.; Defrancq, E.; Lhomme, J. Tetrahedron the influence of these processes on the carbonyl 1997, 53, 5485-5492. b) Houdier, S.; content and on the carbonyl distribution of pulps Legrand, M.; Boturyn, D.; Croze, S.; was analyzed. Defrancq, E.; Lhomme, J. Anal. Chim. Acta 1999, 382, 253-263. c) Houdier, S.; 97

Perrier, S.; Defrancq, E.; Legrand, M. Anal. Chim. Acta 2000, 412, 221-233. [11] Röhrling, J.; Potthast, A.; Rosenau, T.; Lange,T.;Borgards,A.;Sixta,H.;Kosma, P. Synlett 2001, 5, 682-684. [12] Röhrling, J.; Potthast, A.; Rosenau, T.; Adorjan, I.; Hofinger, A.; Kosma, P. Carbohydr. Res. 2002, 337, 691-700. [13] For the detailed method optimization see: Röhrling, J., Ph. D. Thesis, University of Technology / University of Agricultural Sciences, Vienna 2002 and Röhrling, J.; Potthast, A.; Rosenau, T.; Lange, T.; Ebner, G.; Sixta, H.; Kosma, P. Biomacro- molecules 2002, published on the web as ASAP paper. [14] Röhrling, J.; Potthast, A.; Rosenau, T.; Lange,T.;Borgards,A.;Sixta,H.;Kosma, P. Biomacromolecules 2002, published on the web as ASAP paper. [15] Sixta, H. Das Papier 2001, 55, 22-31. [16] The same principle was used for instance by Fischer et al. to determine the xanthogenate groups in viscose samples or methyl groups in methyl cellulose: Fischer, K.; Koch, R.; Fischer, M.; Schmidt, I. Das Papier 1999, 53, 722-727. [17] Strictly speaking, introduction of carbonyl groups by oxidative modifications of cellulose is no “substitution”, so that usage of the expression “degree of substitution” would be inappropriate. Nevertheless, the term shall be maintained for convenience. [18] Chirat, C.; Lachenal, D. Holzforschung 1994, 48 Suppl., 133-139. [19] Olkkonen, C.; Tylli, H.; Forsskahl, I.; Fuhrmann, A.; Hausalo, T.; Tamminen, T.; Hortling, B.; Janson, J. Holzforschung 2000, 54, 397-406. 98

THE BIOHOCH®-REACTOR: STATE OF THE ART IN BIOLOGICAL WASTER TREATMENT IN THE VISCOSE FIBRE INDUSTRY

Wolfgang Ott

Acordis Kelheim GmbH, Regensburger Straße 109, D - 93 309 Kelheim, Germany phone: +49 9441 99394, fax: +49 9441 99228, e-mail: [email protected]

A major development in our society has been To achieve a continuous and sustainable taking place over the past years, and its pace improvement in environmental protection, is steadily accelerating: people have never state-of-the-art technologies have been been more aware of dangers for the implemented. For the wastewater sector - environment - and hence for themselves. especially in the viscose industry - the role of Governments are showing a great alertness for the leader in technology is filled by the emissions of any kind, regulations imposed on BIOHOCH-reactor. Its low operational costs, the industry are constantly becoming stricter. high energy efficiency and high decomposition Not only is environmental protection an rates fulfill the expectations in every area and increasingly growing cost factor, industry offer sound reserves in capacity and itself is agreeing on programs such as operational security. The following article “Responsible Care“ to fulfill its should give you a deeper insight in its design responsibilities as a key player in our natural and operation method. and social environment. ______

Introduction This paper does not intend to give a report about The discussion about the Best Available the development of IPPC and the necessities Technologies, now known under the term of resulting from the BREF, it presents an impression, BREF has been a permanent discussion since the how Best Available Technology could be defined 90s, when the industry made its commitment on the wastewater sector. The BIOHOCH® reactor towards Responsible Care and also Sustainable is surely not the only way to treat wastewater, but Development. For example our chemical union it is indeed a very good one. defined a target to reduce on average the COD- load of 20 % within the next 10 years. Historical development of wastewater treatment Legal necessity Before going into the technical details a short Within the European implementation of the overview about the history of wastewater IPPC regulations and the discussions about the treatment may be of interest. A proverb says, BREFS some European members may see the “Rome was not built in a single day”; its the same necessity of acting. for the development of the BIOHOCH® reactor. The meaning of these abbreviations in exact Three development stages exist within the total wording is: process: BREF = Best Available Technique Reference Documents. The BREF are discussed within the IPPC-regulations. IPPC = Integrated Pollution Prevention Control. 99

• 1963: Construction of a waste water pilot Waste water treatment – how does it work? plant at the beginning of extensive trials for biological treatment of production For better understanding the principles of wastewater wastewater treatment are explained and the details • 1967: Start-up of the unit I of the central on the technologies involved are given. biological waste water treatment As it is so often the case, nature itself played the • 1977: Start-up of the unit II of the central role model for the sewage treatment system. In the biological waste water treatment narrow confines a full biological sewage treatment • 1981: Start-up of the unit III: BIOHOCHâ works, the same processes as in the natural water reactor in Kelheim (the first in the world) systems take place with high degree of efficiency. • 1991: the second BIOHOCHâ-reactor Everywhere there are harmless bacteria, which went into operation. absorb the oxidizable organic substances dissolved We would like to highlight the year 1981: after in the water; the bacteria then transform the 5 years of research time the first BIOHOCH® pollutants into harmless substances, such as carbon reactor in the world went into operation in dioxide and water. The bacterial mass grows Kelheim. 10 years of experience later, we built forming surplus sludge, which has to be removed the second one in 1991 in a slightly different for disposal. design.

Principle of the BIOHOCH® reactor

To treat wastewater a few different technologies exist. To be able to understand the specifications of the BIOHOCH® reactor, Figure 1 shows you in an impressive way how different the two technologies are. A BIOHOCH® reactor consists of a cylindrical tank, an activated sludge basin where the biological decomposition takes place, and a final sedimentation basin shaped like a inverted truncated cone surrounding the activated sludge basin (Figure 2). The oxygen required for the biological decomposition is taken from finely dispersed air. This is one of the great specialties of this BOD plant. The air is produced by screw compressors and injected through special nozzles at the bottom of the activated sludge basin. In the final sedimentation basin the bacterial mass is separated from the cleaned wastewater by sedimentation. While the biggest part is returned to the activated sludge basin to re-continue its decomposition work, a small part is removed as surplus sludge. One of the advantages of this design is that it requires no sludge recycling pumps. A self-feeding current evolves due to the differences in density between the activated sludge basin (low density) and the final sedimentation Figure 1. Comparison between flat BOD-plant and the ® basin (high density). BIOHOCH reactor. A further special feature of the BIOHOCH® reactor is that it has a simultaneous nitrification 100 and denitrification effect when the oxygen By describing the BOD plant, the special air content of the activated sludge basin is set injection (Figures 4 and 5) was already mentioned. correctly. This is only of interest if you are The central elements in any BIOHOCH reactor are dealing with mixed wastewater, such as that radial-flow jets. These are two-component nozzles, handled in Kelheim. Both viscose and acrylic in which the air is dispersed by a water jet, forming wastewater are treated. fine bubbles before being radially distributed by To get more security additional flotation units means of circulation tubes in the liquid to be have been installed; each reactor is followed by aerated; this causes a uniform distribution over a these systems (Figure 3). Residual flakes are large area. separated in four basins to produce a non-turbid outflow of purified water. This is achieved by injection of air. The air bubbles are adsorbing the sludge and transport it to the surface. A reamer system is removing the sludge from the surface.

Figure 2. Structure of a BIOHOCH®-reactor.

Figure 4. Aeration system: jet circulation tubes.

Figure 3. Flotation system.

In the following, a short overview over the most important technical data is presented. Especially we want to point out the high COD-degradation and the low energy consumption. Figure 5. Aeration system: radial flow. 101

to achieve a better distribution of air by the optimized circulation. The 10 years of experience Figure 6 shows the exact principle of this showed that this installation is not necessary. To aeration system. Water is injected from the describe the exact kinetic advantages would take bottom, compressed air from the top. At the too much space, but the principle behind them distribution plate we get fine dispersed bubbles. should be understood. The higher the amount of injected air is, the Figure 7 gives an impression what effect the BOD finer become the bubbles. Fine dispersed bubbles plant had on the effluent COD loads over the have a large surface area and therefore years. Smaller modifications in the process and at guarantee extremely high oxygen utilization. In the BOD plant will be the key for a steady further our first reactor (1981) we have also installed improvement, as it is requested according to the so-called guiding-tubes. Our intention was EMAS and Responsible Care.

Figure 6. Principle of aeration system.

16000

14000

12000

10000

8000

COD (kg/d) 6000

4000

2000

0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001

Figure 7. Development of the COD loads. 102

BHR 1 BHR 2 Height of liquid column [m] 15 15 Capacity of activated sludge tank [m3] 3.000 5.400 Surface of final sedimentation basin [m2] 250 550 Capacity of final sedimentation basin [m3] 1.450 3.810 Max. sewage throughput [m3/h] 200 440 Number of air injection nozzles 721 Max. total air input [m3/h] 10.000 COD-load [kg/d] 15.000 Oxygen utilization [%] ≈ 50 Efficiency of decomposition COD [%] ≈ 95 Efficiency of decomposition nitrogen [%] ≈ 80 Energy consumption as a function of decomposed COD [kWh/kg] ≈ 0,8

Table 1. Technical data of the BIOHOCH reactor.

Conclusion • Optimum air injection based in radial flow nozzles, The BIOHOCH®-reactor is a real alternative for • High degree of oxygen utilization saves all who aspire a satisfying and permanent costs, solution on the wastewater sector. The final • Minimum noise and odor nuisance, listing of advantages should emphasis this: • A freely accessible tank design that ensures • High-rise design requires extreme little optimum operational reliability. space, • Short construction times mean economical installation,